When we bought our trailer they brought us sheets detailing the payment at different interest rates and years of payment. We chose one, signed and took the rig a few days later and left on a 16 day trip. In the middle of the trip our salesperson called to say there had been a mistake and we needed to come in right away. We were hundreds of miles away and told them it would have to wait.
Then they called the next day and the day after that. About the time they started to get a bit nasty about it I told them if I had to pack it up and end my vacation that I would be stopping at home to unload as they could just keep the trailer. That got them to leave us alone until the trip was done.
When I did get back and go in the manager met me and said that they couldn't figure it out but the payments didn't match up with the total cost of the rig and we had a choice of redoing the payments OR return the trailer.
It took me a hour to find the mistake, someone took the sale price of the trailer before interest, taxes and dealer fees and broke that up into 5 years worth of payments. leaving the rest unpaid. Since the price of the rig hadn't changed we redid the payments. Had the tried to get a penny more, they could of had it back.
I don't know what would have happened if we refused, I believe we would have legally owed for the rest. In the end the manager gave us a gift card for figuring it out and as I left I could hear him in the financing office going on about how they had to weeks and couldn't find what a customer did in a hour.