That letter from the bank can be a nasty surprise. A creditor has levied (frozen) your bank account! What do you do? How do you defend yourself? In most instances, there are no defenses.
However, if your name is on the account is merely for convenience and none of the money is yours, or if the money is a Social Security or VA benefit (or some other non-leviable asset), then you can object. You can also limit the levy amount if some of the money in the account belongs to someone who is not a defendant with you.