public ActionResult Configure()
        {
            var model = new ConfigurationModel();
            model.AdditionalFee = _purchaseOrderPaymentSettings.AdditionalFee;
            model.AdditionalFeePercentage = _purchaseOrderPaymentSettings.AdditionalFeePercentage;

            return View("Nas.Plugin.Payments.PurchaseOrder.Views.PaymentPurchaseOrder.Configure", model);
        }
        public ActionResult Configure(ConfigurationModel model)
        {
            if (!ModelState.IsValid)
                return Configure();

            //save settings
            _purchaseOrderPaymentSettings.AdditionalFee = model.AdditionalFee;
            _purchaseOrderPaymentSettings.AdditionalFeePercentage = model.AdditionalFeePercentage;
            _settingService.SaveSetting(_purchaseOrderPaymentSettings);

            return View("Nas.Plugin.Payments.PurchaseOrder.Views.PaymentPurchaseOrder.Configure", model);
        }