Schoolbus, you've GOT to get rid of that car and walk away. You're paying almost twice the car's value! NO STINKIN' WAY.
Call them back,. with that recorder function I told you about, and get them on tape saying she can return the car and walk away. You're in NC, so you don't have to have their permission or knowledge to record the conversation. Then take that car back and WALK OUT.
You have GOT to be the "type of person" to be hostile if that's what it takes. They are trying to hold you by the peanuts by mentioning messing up the closing on the house. Well, unless they suddenly put it on your CR, they can't. The inquiries are already going to be there. The longer it takes them to secure financing, the more they are letting other banks put inqs on your Mom's CR. So really, they're messing up the closing by forcing you to stay in the car while they bombard the CR with inquiries.
The car is not worth it, mechanically or financially. Get it on recorder that they'll elt her return it, and then RETURN IT. Do it mid-day, with lots of customers around. It takes GUTS, but you must do it or your Mom will be in an even bigger financial bind than she already has been. My pmt is $500, and that is for a pimped-out Rendezvous SUV with leather and SUEDE interior, alloy wheels, navi system, real wood trim inside, Bose sound system, etc. No way should she pay the same amount for a Sonata.
Bring the recording with you and DON'T be afraid to play it if you have to.
I had to grab my guts and tell the mgr of the salon that butchered my hair that I was going to dispute the transaction and contact the BBB if she tried to charge me for the cut/color, and it was HARD. My heart was pounding when I talked to her. But it was worth it. I got ALL my money back because she realized I wasn't going to be walked over.