What do you do if a bank sells a car the repo'd for too little.?

Maybe you are missing the fact that the bank is not going to invest the time and work or money it takes to actually keep the car for as long as it takes to find a buyer willing to pay a reasonable price. From their point of view, they are just reducing their loss as soon as possible without caring about what may happen to your finances once you are past the point where you are still in control because you have the car. The bank doesn't care about you. They want to cut their losses but if you do become able to pay at some time in the future, the bank just sees you as a cash cow. Can you get any proof that the car was indeed sold for so little? Then, maybe it was. The bank recovered their asset and still has you on the hook for further payments, so that's all right with them.

You may have to file a claim in court demanding all the paperwork on the sale. When it was sold, who bought it, sales price. They must sell it at a fair price. However, what is a fair price? That isn't defined in any law book. Just because they 'told' you it was sold for $2,200 doesn't mean the actually did. They aren't going to let a good, clean running car go for $2,000 when they could have gotten more. There's no guarantee the will get the difference from you. They would have and should have sold it for more than $2,000. In any lawsuit, the plaintiff is required to mitigate their damages. In this case, they did not. You may need a lawyer's advice.

Repo'd cars are sold at auction and always go cheap. It isn't uncommon for the balance due to be almost as much as the loan balance, especially after adding fees for the repo and auction.

You would have been much better off to have sold the vehicle yourself and paid the loan difference.

$12,500 by who's estimate? The loan company sells cars at auction where the prices are always low. This is why you should have sold it yourself. There is nothing that you can do except pay what you owe.

Ohhhhhh - how can I tell you - they lied! If you read the contract when you bought the automobile you would see that they can sell it for any amount and you are stuck paying off the loan!!! FAIR - heck no - but why do you think there are so many Auto Loan companies around - they make money either way.