Hi, my warranty has expired

by 4,000 miles and of course Chrysler financial won't help out. Chrysler Alhambra, Ca, (independently owned) denies all of it. They even put a huge gash on the roof which the service manager replied", It looks like someone has painted over this car". But what the jackas* failed to realize was i bought the car brand new, which i quickly told him. First i have to have the computer fixed ($2,000), just to find out what the problem is.
As for EZLUBE, they accepted full responsibility by putting in a USED differential. I need a good lawyer and if any one has any suggestions a good mechanic. Also do you know how or where I can find maybe a salvaged computer module? Correct me if I'm wrong but isn't the computer basically the whole brain of the car? I love this car and don't want to lose it. I've halfway paid it off.

Thanks again for the help.