The amount does not make sense to me and you should be in control through your bank; the debt collector cannot just take what amount they want (or, you should set up your bank account so they cannot). I would go to your bank and work through what was paid to whom, when, with them; it sounds like a bank error to me. If it turns out the debt collector did withdraw money improperly and you cannot get it resolved with them, I would write the hospital's attorney (just address it to "Such-and-such hospital Attorney's Office", and the hospital address) and explain your problem and see if they can help by reining in the debt collector.