We also encountered this problem since last thursday, we even doubted that our sandbox account is forbidden for some reason. But when I tried to pay again this morning, it appears that problem has been solved, as if nothing happend before!
Just have a try!!!
kevonyang
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution