1996 Honda Civic Clutch replacement

I just had my clutch replaced. Ever since then the car rides rough. It shakes, it is jerky. It really feels like I am going over little bumps whenever I am driving. Also sometimes when I start it, it sounds like the transmission is going to fall out. There is a noise like a thump when I start it. My car drove smooth before they did this clutch job. I've taken it back 3 times. They act like I am crazy. I would like to go back there with a little knowledge on what might be the problem so they don't dismiss me. I thought a new clutch should make the car run nice a smooth.