What happened to you is clearly not your fault, but after having similar issues with big institutions, I've realized that doing more than one "important" operation on a " big business/bank" account is always finicky.

So now I do things one at a time.

E.g. To cancel a card, first move all money (or debts) from acct A to acct B. Go home. Couple of days later, pay any outstanding fees of acct A. Go home. Couple of days later, request cancellation. Inevitably find that something else needs to be done, so do that thing. Go home. Couple of days later....

You get the idea. It sucks big time, but I've found it's better that way, since the probability of error is somewhat lower (and even then it happens!)