I had a similar experience with Chase. I had two cards with no balance, but there was some interest charges. They kept sending bills with 0 balance, but then would send overdue notices for the interest--but only listed the new interest amount, not the total accumulated interest. So basically I was paying off what they'd say was due, but was still accumulating interest. This went on for a few months. Finally I called them and yelled at them to the point I got ahold of the queen customer service nazi, paid them and got them closed on the spot.

Now we live totally off the ATM and Costco Amex.