public HttpResponseMessage GetBalance(string cardNumber, string pin)
        {
            Validate(cardNumber, pin);

            try
            {
                var balance = _bankCardService.GetBalance(cardNumber);
                return(Request.CreateResponse(HttpStatusCode.OK, balance));
            }
            catch (Exception ex)
            {
                Log.Error("Unexpected error has occured while updating pin code. Bank card: " + cardNumber, ex);
                throw;
            }
        }