What is the CA state maximum a dealership can charge me if I return a car after the loan was declined?

I traded in my car for $2100 towards an $8000 vehicle. I have had the car for nearly 4 weeks and the 1st bank declined my loan. The dealership sent me to another bank where I have recently completed a phone interview. This car has been having many problems including needing a new timing belt and the check engine light illuminating, and I need to know what I face should the loan be declined or should it be returned at a higher interest rate than I agreed to. I looked over my contract and it shows a $350 restocking fee within the first 3 days if I decide to return the car. Where can I find out vehicle codes or buyers rights? Will I get my old car back or a check for the trade in value minus what ever fees they decide to charge?