Bought vehicle from drivetime only had truck for a week started leaking oil. Took car to the warranty approved shop. Long story short truck is in shop for a week has not been repaired needs oil pan gasket rear and front seals and silver rock is giving me the run around

Got a 2008 Nissan Altima for $10,000 on January 15, 2016. Right away within the 30 day warranty it started to take awhile for it to speed up. Ask that is be checked at there onsite garage. Was told I'd have to pay $50 just for them to look at it. Was told nothing was wrong. Went to Midas for an oil change in May 2016, was told that I needed to replace the engine torque, power steering pump along with the hoses and filters, and transmission. Called Drivetime and told them and they said again I would have to pay $50 for them to just look at it. Now currently, May 2017, car is having MAJOT problems and I go to try to trade-in with another dealer so that they can buy the loan I have with Drivetime. Come to find out the my car is only worth $4,979 and they have charged me with over $4,000 interest on the car loan. The pay out is $14,975. Also I was told that this is considered a predatory loan and should just voluntary repossess the car and in 3 years it should be default off my credit but I don't know what to do. Need transportation.