Sounds as though it is time to use the billing error procedure--by the way, I agree that it is better to use Amex if you can.

Anyhow, notify Chase at the special billing error address on your bill via u.s. mail (email, fax or phone don't count) with proof of delivery (enclosing a check as payment on your account may do if you note the enclosure in your letter) and follow Fair Credit Billing Act procedures for defective merchandise.