ThriftBooks review: Placing an order with a new card

Started causing a problem on 9/21. I tried to enter a new credit card was rejected at least 7 times. When I called in , after a much too long wait, the Rep said she could not help me alter anything and to try again. The exp date on the card reads 08/31.The screen always says 08/2031. The rep says don't use slashes - but they're there. The new card number has shown up as an icon three times already. Does Thriftbooks have anyone there who can help me with this problem? I have been a customer for many years.