diff --git a/app/classes/Framadate/FramaDB.php b/app/classes/Framadate/FramaDB.php
index 00a1b83..b8c6c79 100644
--- a/app/classes/Framadate/FramaDB.php
+++ b/app/classes/Framadate/FramaDB.php
@@ -79,13 +79,6 @@ class FramaDB {
         return $this->pdo->query($sql);
     }
 
-    function allCommentsByPollId($poll_id) {
-        $prepared = $this->prepare('SELECT * FROM `' . Utils::table('comment') . '` WHERE poll_id = ? ORDER BY id');
-        $prepared->execute(array($poll_id));
-
-        return $prepared->fetchAll();
-    }
-
     function allUserVotesByPollId($poll_id) {
         $prepared = $this->prepare('SELECT * FROM `' . Utils::table('vote') . '` WHERE poll_id = ? ORDER BY id');
         $prepared->execute(array($poll_id));
@@ -205,36 +198,12 @@ class FramaDB {
         return $prepared->execute([$poll_id]);
     }
 
-    /**
-     * Delete all comments of a given poll.
-     *
-     * @param $poll_id int The ID of the given poll.
-     * @return bool|null true if action succeeded.
-     */
-    function deleteCommentsByPollId($poll_id) {
-        $prepared = $this->prepare('DELETE FROM `' . Utils::table('comment') . '` WHERE poll_id = ?');
-
-        return $prepared->execute([$poll_id]);
-    }
-
     function updateVote($poll_id, $vote_id, $name, $choices) {
         $prepared = $this->prepare('UPDATE `' . Utils::table('vote') . '` SET choices = ?, name = ? WHERE poll_id = ? AND id = ?');
 
         return $prepared->execute([$choices, $name, $poll_id, $vote_id]);
     }
 
-    function insertComment($poll_id, $name, $comment) {
-        $prepared = $this->prepare('INSERT INTO `' . Utils::table('comment') . '` (poll_id, name, comment) VALUES (?,?,?)');
-
-        return $prepared->execute([$poll_id, $name, $comment]);
-    }
-
-    function deleteComment($poll_id, $comment_id) {
-        $prepared = $this->prepare('DELETE FROM `' . Utils::table('comment') . '` WHERE poll_id = ? AND id = ?');
-
-        return $prepared->execute([$poll_id, $comment_id]);
-    }
-
     function deletePollById($poll_id) {
         $prepared = $this->prepare('DELETE FROM `' . Utils::table('poll') . '` WHERE id = ?');
 
diff --git a/app/classes/Framadate/Repositories/CommentRepository.php b/app/classes/Framadate/Repositories/CommentRepository.php
new file mode 100644
index 0000000..4511390
--- /dev/null
+++ b/app/classes/Framadate/Repositories/CommentRepository.php
@@ -0,0 +1,59 @@
+<?php
+namespace Framadate\Repositories;
+
+use Framadate\FramaDB;
+use Framadate\Utils;
+
+class CommentRepository extends AbstractRepository {
+
+    function __construct(FramaDB $connect) {
+        parent::__construct($connect);
+    }
+
+    function allCommentsByPollId($poll_id) {
+        $prepared = $this->prepare('SELECT * FROM `' . Utils::table('comment') . '` WHERE poll_id = ? ORDER BY id');
+        $prepared->execute(array($poll_id));
+
+        return $prepared->fetchAll();
+    }
+
+    /**
+     * Insert a new comment.
+     *
+     * @param $poll_id
+     * @param $name
+     * @param $comment
+     * @return bool
+     */
+    function insert($poll_id, $name, $comment) {
+        $prepared = $this->prepare('INSERT INTO `' . Utils::table('comment') . '` (poll_id, name, comment) VALUES (?,?,?)');
+
+        return $prepared->execute([$poll_id, $name, $comment]);
+    }
+
+    function delete($poll_id, $comment_id) {
+        $prepared = $this->prepare('DELETE FROM `' . Utils::table('comment') . '` WHERE poll_id = ? AND id = ?');
+
+        return $prepared->execute([$poll_id, $comment_id]);
+    }
+
+    /**
+     * Delete all comments of a given poll.
+     *
+     * @param $poll_id int The ID of the given poll.
+     * @return bool|null true if action succeeded.
+     */
+    function deleteByPollId($poll_id) {
+        $prepared = $this->prepare('DELETE FROM `' . Utils::table('comment') . '` WHERE poll_id = ?');
+
+        return $prepared->execute([$poll_id]);
+    }
+
+    public function exists($poll_id, $name, $comment) {
+        $prepared = $this->prepare('SELECT 1 FROM `' . Utils::table('comment') . '` WHERE poll_id = ? QND name = ? AND comment = ?');
+        $prepared->execute(array($poll_id, $name, $comment));
+
+        return $prepared->rowCount() > 0;
+    }
+
+}
diff --git a/app/classes/Framadate/Repositories/RepositoryFactory.php b/app/classes/Framadate/Repositories/RepositoryFactory.php
index 2c0821b..6e2437d 100644
--- a/app/classes/Framadate/Repositories/RepositoryFactory.php
+++ b/app/classes/Framadate/Repositories/RepositoryFactory.php
@@ -26,6 +26,7 @@ class RepositoryFactory {
 
     private static $pollRepository;
     private static $slotRepository;
+    private static $commentRepository;
 
     /**
      * @param FramaDB $connect
@@ -56,4 +57,15 @@ class RepositoryFactory {
         return self::$slotRepository;
     }
 
+    /**
+     * @return CommentRepository The singleton of CommentRepository
+     */
+    static function commentRepository() {
+        if (self::$commentRepository == null) {
+            self::$commentRepository = new CommentRepository(self::$connect);
+        }
+
+        return self::$commentRepository;
+    }
+
 }
diff --git a/app/classes/Framadate/Services/AdminPollService.php b/app/classes/Framadate/Services/AdminPollService.php
index 70699bb..4e4f9d6 100644
--- a/app/classes/Framadate/Services/AdminPollService.php
+++ b/app/classes/Framadate/Services/AdminPollService.php
@@ -2,7 +2,7 @@
 namespace Framadate\Services;
 
 use Framadate\FramaDB;
-use Framadate\Utils;
+use Framadate\Repositories\RepositoryFactory;
 
 /**
  * Class AdminPollService
@@ -14,17 +14,23 @@ class AdminPollService {
     private $connect;
     private $pollService;
     private $logService;
+    private $pollRepository;
+    private $slotRepository;
+    private $commentRepository;
 
     function __construct(FramaDB $connect, PollService $pollService, LogService $logService) {
         $this->connect = $connect;
         $this->pollService = $pollService;
         $this->logService = $logService;
+        $this->pollRepository = RepositoryFactory::pollRepository();
+        $this->slotRepository = RepositoryFactory::slotRepository();
+        $this->commentRepository = RepositoryFactory::commentRepository();
     }
 
     function updatePoll($poll) {
         global $config;
         if ($poll->end_date > $poll->creation_date && $poll->end_date <= strtotime($poll->creation_date) + (86400 * $config['default_poll_duration'])) {
-            return $this->connect->updatePoll($poll);
+            return $this->pollRepository->update($poll);
         } else {
             return false;
         }
@@ -38,7 +44,7 @@ class AdminPollService {
      * @return mixed true is action succeeded
      */
     function deleteComment($poll_id, $comment_id) {
-        return $this->connect->deleteComment($poll_id, $comment_id);
+        return $this->commentRepository->delete($poll_id, $comment_id);
     }
 
     /**
@@ -49,7 +55,7 @@ class AdminPollService {
      */
     function cleanComments($poll_id) {
         $this->logService->log("CLEAN_COMMENTS", "id:$poll_id");
-        return $this->connect->deleteCommentsByPollId($poll_id);
+        return $this->commentRepository->deleteByPollId($poll_id);
     }
 
     /**
@@ -81,12 +87,12 @@ class AdminPollService {
      * @return bool true is action succeeded
      */
     function deleteEntirePoll($poll_id) {
-        $poll = $this->connect->findPollById($poll_id);
+        $poll = $this->pollRepository->findById($poll_id);
         $this->logService->log('DELETE_POLL', "id:$poll->id, format:$poll->format, admin:$poll->admin_name, mail:$poll->admin_mail");
 
         // Delete the entire poll
         $this->connect->deleteVotesByPollId($poll_id);
-        $this->connect->deleteCommentsByPollId($poll_id);
+        $this->commentRepository->deleteByPollId($poll_id);
         $this->connect->deleteSlotsByPollId($poll_id);
         $this->connect->deletePollById($poll_id);
 
@@ -179,7 +185,7 @@ class AdminPollService {
      * @return bool true if added
      */
     public function addSlot($poll_id, $datetime, $new_moment) {
-        $slots = $this->connect->allSlotsByPollId($poll_id);
+        $slots = $this->slotRepository->listByPollId($poll_id);
         $result = $this->findInsertPosition($slots, $datetime, $new_moment);
 
         // Begin transaction
diff --git a/app/classes/Framadate/Services/PollService.php b/app/classes/Framadate/Services/PollService.php
index a5301de..4cc7fa1 100644
--- a/app/classes/Framadate/Services/PollService.php
+++ b/app/classes/Framadate/Services/PollService.php
@@ -28,12 +28,14 @@ class PollService {
     private $logService;
     private $pollRepository;
     private $slotRepository;
+    private $commentRepository;
 
     function __construct(FramaDB $connect, LogService $logService) {
         $this->connect = $connect;
         $this->logService = $logService;
         $this->pollRepository = RepositoryFactory::pollRepository();
         $this->slotRepository = RepositoryFactory::slotRepository();
+        $this->commentRepository = RepositoryFactory::commentRepository();
     }
 
     /**
@@ -51,7 +53,7 @@ class PollService {
     }
 
     function allCommentsByPollId($poll_id) {
-        return $this->connect->allCommentsByPollId($poll_id);
+        return $this->commentRepository->allCommentsByPollId($poll_id);
     }
 
     function allVotesByPollId($poll_id) {
@@ -75,8 +77,11 @@ class PollService {
     }
 
     function addComment($poll_id, $name, $comment) {
-        // TODO Check if there is no duplicate before to add a new comment
-        return $this->connect->insertComment($poll_id, $name, $comment);
+        if ($this->commentRepository->exists($poll_id, $name, $comment)) {
+            return true;
+        } else {
+            return $this->commentRepository->insert($poll_id, $name, $comment);
+        }
     }
 
     public function countVotesByPollId($poll_id) {