Mubby,
I have read about the issues you have had on the other thread. Of course you must be disappointed.
During a presale the site's servers get quite overloaded so some technical glitches happen. Cards not being accepted are one of those, others lose the content of their shopping cart in the process, the list is long. Other major artist's websites regulary go down completely for hours during presales, Robbie Williams is a well known example.
Since you stated to have made purchases with your card before this kind of card seems to get accepted. Otherwise the shop would not offer the option.
Hopefully you will be able to find good tickets in the general sale on Friday.
All the best, Rena