X-Cart forums - X-Payments not recognizing coupon codes

We went through several weeks of frustration while trying to install X-Payments ourselves. We finally resorted to having Qualiteam install it for us ($258.00). The install was completed on 7/18/2012.

I use PayPal Payments Pro. Customers can either use their credit card (which takes them to X-Payments) or use the Express Checkout which takes them to PayPal to remit payment.

We just discovered that customers using a credit card via X-Payments are unable to complete their transaction if they've used a coupon code (coupon code generated in X-Cart). If the customer is using Express Checkout there is no issue using a coupon code. PayPal recognizes the coupon codes, X-Payments does not.

The error message received when the transaction is declined because a customer attempts to use a coupon code is:

Reason: Error: Transaction refused because of an invalid argument. See additional error messages for details. (The totals of the cart item amounts do not match order amounts.)

Before X-Payments there were no issues with using a coupon code if the customer was using a credit card for payment. There are no issues now if the customer uses the PayPal Express Checkout.

This sounds to me as if there is some setting not active in X-Payments or perhaps a bug that doesn't take into the 'equation' that a customer is using a coupon code.

I contacted Qualiteam and they promptly responded that I have no service points with my X-Cart so they cannot assist me. This befuddles me because I don't think this issue is with X-Cart, it's with X-Payments, a program they installed last month.

I was directed to use the forums -- or I suppose I could pay $99 to have Qualiteam investigate, but on top of the already $258 I shelled out to have them install X-Payments I'm a bit hard pressed to do that.

Has anyone experienced this issue with X-Payments not recognizing X-Cart coupon codes? And if so, how do we correct this?

Since we did not install X-Payments we have no idea where to begin to correct this issue.

(And yes, I do realize I'm venting a wee bit here, as well, but I'm a bit exasperated). :?

Thank you for your help.

X-Payments 1.0.4 (really??? We just had this installed).