I bet AT&T may disagree.
I was told you cannot close an account, ever, for merchants. When you "close" it, you only essentially tell the bank that you no longer want to get statements, and they will stop charging you the monthly maintenance fee. Also, if you do write a check after "closing" the account, they will deny the payment (I guess that is bank dependent) but in all cases you will be charged an overdraft fee. Once you open an account, it will be there for life and even through death it will be passed to your heirs.
They apparently have no mechanism to filter an incoming electronic debit request when the account is closed because they keep the account number in their logs. Closing an account is not "deleting" an account.