F&I basically said the paperwork was done wrong, and that I owed him another $3K + tax. I said I wasn't sure what he was talking about, and didn't have the paperwork in front of me, and that I'd have to go home and look since I'm at work. I asked him again what went wrong and he just said "well, you agreed on a purchase price of $X, and a mistake was made in the sell price that was written on the contract". So I asked him if it was an accounting mistake and he said yes.
It's not an accounting mistake. He says its a mistake in the event that he put in the wrong selling (start price) of the car, there is no accouting mistake proof.
I don't know what to tell him, how to proceed?