public dynamic MobileB2B(string productName, string provider, string transferType, string currencyCode,
                                 int amount, string destinationChannel, string destinationAccount)
        {
            var b2BData = new B2BData()
            {
                Username           = _username,
                ProductName        = productName,
                Provider           = provider,
                TransferType       = transferType,
                CurrencyCode       = currencyCode,
                Amount             = amount,
                DestinationChannel = destinationChannel,
                DestinationAccount = destinationAccount
            };

            try
            {
                string b2Bresponse = PostB2BJson(b2BData, PAYMENTS_B2B_URLString);
                return(b2Bresponse);
            }
            catch (Exception ex)
            {
                throw new AfricasTalkingGatewayException(ex);
            }
        }
            public string PostB2BJson(B2BData dataMap, string url)
            {
                var client = new HttpClient();

                client.DefaultRequestHeaders.Add("apiKey", _apiKey);
                var result = client.PostAsJsonAsync <B2BData>(url, dataMap).Result;

                result.EnsureSuccessStatusCode();

                var stringResult = result.Content.ReadAsStringAsync().Result;

                return(stringResult);
            }