GRE Rescheduling ERROR 481

I am trying to reschedule my GRE. But while payment it is showing the error–There was an error processing your payment (Error:481).
I have tried everything as changing browsers, clearing the cache, then I contacted with the bank for card issue. But there is not any problem in my card. Now, what can I do?

Try to contact ETS customer service.

Here is a number if you want to have a phone call:

+1 (866) 473-4373

Actually, there was a problem in my card. I solved the problem by paying with another card.