I've already solved this problem by buying from somebody other than adagio, but wanted to point out that if an expired credit card and/or an address update on an account puts your checkout in an endless loop of "your card has expired" warnings, even when I enter a new card, and you don't provide a way for the customer to contact you (no phone number, no response to "chat',) you FAIL customer service.
Sorry for the confusion you encountered in the checkout. The ability to update your credit card is fairly straightforward. You simply select the new expiration date and it is automatically updated. As for the unresponsiveness to chat, I must apologize. The chat feature is new for us and we are still working out some bugs on our end. If you have any additional questions, we will be happy to answer your emails.