Car started jumping when put into reverse

I took my car to the mechanic because I noticed that the car would give a slight jump sometimes when I put it in reverse. They said my transmission pan needed to be replaced. After they worked on it, I started having more problems with it jumping really hard. I took it back and they said it must be a transmission problem but they do not work on transmissions (which was upsetting because they should have said that before they did any work). Anyways, l also started having problems while I was driving. I would sometimes get a jerk when I would be at about thirty miles. Now it is jerking more consistently and a lot harder. It even does it when I am at twenty miles, which is new. I have been afraid to drive it. I want to know what kind of problem/expensive I may be looking at? Any recommendations for someone in the L.A. area that works on Saturn's? Thanks in advance!