When you submit your payment details, our credit card processor passes on the information to your bank, who then checks this information. If your card is not passing validation it could mean that:
The billing address you have provided doesn't match what your bank has on file.
The card doesn't have sufficient funds.
A couple things you can do:
Try completing your purchase with a different credit card
Call your bank directly to verify the billing information is correct.
Try using previous billing addresses (it could be that your credit card is still associated with your old address).
Have someone (family, friend, etc.) purchase the tickets for you and pay them back.
Try using a different browser.
If you have any more questions or confusions feel free to email us at firstname.lastname@example.org!