I had the same issue - I upgraded 2 accounts and couldn't upgrade the rest. It has nothing to do with your bank or your credit card. I've tried three different credit cards - all resulted in the same 202 error. Blizzard told me that it is likely that all my cards had problems. Yeah, right. I went to the store and got the retail boxes. If you plan to upgrade to the BC, retail boxes are cheaper.

Hope this helps