public TransactionObject UnsendFriendRequest(int senderUserID, int receiverUserID)
        {
            TransactionObject response = new TransactionObject();

            if ((frManager.CheckExistence(senderUserID, receiverUserID)))
            {
                try
                {
                    User senderUser = userManager.GetUser(senderUserID);
                    User receiverUser = userManager.GetUser(receiverUserID);
                    FriendRequest fr= frManager.GetFriendRequestByUsernames(senderUserID, receiverUserID); ;

                    senderUser.SentFriendRequests.Remove(fr);
                    receiverUser.ReceivedFriendRequests.Remove(fr);

                    frManager.DeleteRequest(fr);
                    uow.Save();
                }
                catch (Exception ex)
                {
                    response.IsSuccess = false;
                    response.Explanation = base.GetExceptionMessage(ex);
                }
            }
            else
            {
                response.IsSuccess = false;
                response.Explanation = "This friend request has not been sent before!";
            }

            return response;
        }