Sue them: bring a lawsuit seeking both monetary compensation (for any amounts you paid after it was cancelled) and for a court order (such as in the form of a "declaratory judgment," or official court determination) that the account has been cancelled. When a business will not do what they should do voluntarily, you need a court to order them to do it. The easier way to do this is with a small claims suit just for any charges, etc. they took out, to recover the money; in the course of that suit, they can agree (in an enforceable way; e.g. by an agreement approved by the court, to settle the matter, as directed by the judge on the record) to close the account.