2000 Ford Contour - HELP

I have a 2000 Ford Contour 4-Cyl that while driving down the road one day just quite and temp went up. I immediatly turned the car offf so it would not overheat. I had it towed to a repair shop and they said that the timing belt went out. Before this happened the car was running great with no problems and has had normal service. So the shop said it was repiared and I picked it up. However when I picked it up the engine light was on and it hadnt previously. I told them and they said hummm, anyway I start driving down the road and the car had a miss and was slugish when I accelerated. I brought it back the next day and they said I would have to live with it, cuase sometime your valves could have been bent when the timing belt broke and that would cost me alot more to fix. So I decided at the moment to drive it for a while and see how it acted. Well 2 more days past and the car froze up on the road. I got out and noticed that the water pump pully had only one bolt in it and the others were gone and the belt had come off and locked the engine. I called the repair place and they said it was not there fault that they didnt touch the waterpump pully to install the timing belt. Which I said how the heck would 2 bolts had come out if they hadnt, anyway we decided that they would fix that, and I paid 100 dollars to have that done. SO now with a missing engine and a engine light that is on, I bring it back to have it inspected and they said it failed and I needed a head gasket replced to pass it. I want to know and I getting the SHAFT here, is all this possible to have gone wrong at the same time?