That’s their job.
You call to cancel a card, and you immediately get sent to the bank’s card retention department. The folks there have incentives and get bonuses based on how many cards they “save”. Amex is the worst one for this. They’ll keep you on the phone forever trying to get you to stay by offering to waive fees, lower interest rates, free balance transfers, etc....until you almost have to resort to profanity to get them to cancel the card.
Going through that BS now, with BOA!
Cancel credit cards by registered U.S. mail, in it, request a written statement from them that they have closed the account, by law, they must do so.