I'm having the same problem. I tried changing my address, but it still came up saying there was a problem with my credit card number or security code.
Another weird thing happened when I did this. When I changed my mailing address to match my billing address, on the payment page, it auto-filled my foreign address, when before it hadn't auto-filled anything.
Edit: It finally worked! I think logging out and logging back in helped. I also removed MAX Benefits because I heard other people getting errors associated with it.
