I booked a flight to pit a week or two ago on ac.com.

There was some sort of error on the final confirmation screen. Kept telling me that the CC info was wrong. I called the website support line and was told to select an alternate CC option, which opened up a bunch of fields (like name, card type, card number, expiry, etc). I filled in the info and the booking worked.

Just now I logged onto my AC.com account and checked the CC info. It's exactly as is should be. Type, number, expiry, etc. So I don't know why the info that's on-file doesn't work but manually entering the same info did work.