If you believe that a bank has failed to comply with Regulation E (or any other consumer regulation), you should draft a careful letter explaining your position. Include details about what specifically you believe was handled incorrectly. You should first direct the letter of complaint to management of the bank. Aim high here. Call the bank or look at their Web site to determine the name and mailing address of their President, and use it.
While the President of the bank won't be equipped in most cases to resolve the problem him- or herself, he or she will usually want to be certain that the bank has not violated any rules.
If you obtain no satisfaction from the bank's management, and still believe you've been wronged, contact the OCC's Customer Assistance Group. Here's a
LINK to their customer assistance Web page, where you'll find mailing and e-mail addresses, and additional information. The OCC is the regulator for national banks.