/// <summary>
        /// Releases reserved funds
        /// </summary>
        /// <param name="reservationKey"></param>
        /// <returns></returns>
        public void ReleaseFundReservation(Guid reservationKey)
        {
            // get the reservation
            var reservation = CashAccountFundReservations.FirstOrDefault(r => r.ReservationKey == reservationKey.ToString());

            // if reservation was not found, it doesn't exist - just return
            if (reservation == null)
            {
                return;
            }

            // remove the reservation
            CashAccountFundReservations.Remove(reservation);

            // save changes
            SaveChanges();
        }