If you get an AVS error, then no, it's not an error in our system. Our system only responds back to what you put into it. You enter your card number, and your billing address and we process it. During that processing, we ask your bank if they match up. If you bank says no, the transaction is automatically declined.
So, it's possible that your bank has the right information entered in the customer service aspect, but on the security side, they may have an old address; sometimes the left hand and the right hand aren't always talking. I'd suggest you contact your bank and talk to customer service, confirm what they have, then get bumped up to security, and see what they have.