Patrick McKenzie says, Some people edit Wikipedia. Some kept Livejournals. Letters to banks were my primary writing outlet before I discovered business and blogging. It's a quirky hobby, but just trust me that I indeed had it, from approximately 2004 through 2007. post 
You don’t need to do anything just because your data was leaked or might have been leaked.
Do not use the following advice to correct a problem with an account which is factually yours.
Was an account opened in your name without your consent? Great, you’re in the right place.
Communicate with the bank in a manner which suggests that you’re an organized professional who is capable of escalating the matter if the bank does not handle it themselves. Mean words cannot hurt a bank. Threats cannot hurt a bank. Paper trails, though, are terrifying to regulated institutions.
Retain copies of all correspondence with a bank or credit reporting agency (CRA) forever. Erroneously reported debts which you thought were taken care of can be resurrected years later by someone failing to check a box during a CSV export, resulting in the debt getting sold to a new debt collector, who will not know that you spent weeks resolving it. You want your paper trail so that your first and only letter to that debt collector credibly promises armageddon.
People who can file a regulatory action while being emotionless about it are terrifying, because they suggest that their day job is e.g. administrator for a hospital, that they’re very comfortable with pushing papers around government agencies, and that they will remember deadlines, keep copious records, and consult with other professionals where appropriate. People like this have an annoyingly predictable tendency to convince bureaucracies to give them what they want.
If you are dealing with a bank specifically, you can complain to their regulator – bring your paper trail. Banks are regulated by a variety of organizations in the United States and it may not be obvious which to direct your complaint to. You can trivially find this out by either walking in to any branch and asking or calling any of their 1-800 numbers; you may be escalated to a complaints department, but politely insisting “I need to write a letter to your regulator. Who is that, please.” will get you their name within 5 minutes.
You will get through this; you will not have to pay debts which are factually not yours. I share your frustration with The System. It is broken, and it catches innocent people up in its gears far, far too often. You can still win.
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Patrick's tweetstorm in response to the massive Equifax breach got me to read this longer piece. I too have a long interest in bureaucracies and found all of his advice to ring true. twitter