Waxleton, Paizo customer service will be back on Monday. But, in the meantime, I wanted to let you know that the credit card processor is extremely picky about address verification. Check the address you have here at Paizo and compare it to the address you have on file at the bank issuing your card. Even the slightest difference (Street vs St.) could be why your card was declined.
If it still gives you issues, I am sure customer service can pinpoint the problem for you when they are back in the office.