Dead engine after timing belt water pump change?

My car had been had been overheating fans working on and off got them fixed then went to auto shop for new radiator because when the car would overheat radiator would leak so auto shop says I needed to replace it. The mechanic puts in new radiator starts the car turns on ac to see if it would overheat and the car cuts off. He told me he put it on the computer and he checked and the timing belt and water-pumpp need to be changed. He says after this I should be good to go. So I agreed he now says after installing new belt and pump car engine wont start the engine has no compression. He says I need a new engine. This is a service center I already paid for the new radiator job yesterday 223.00 They told me I have to talk to the manager tomorrow I told them I am not paying because I bought my car in running now the engine is shot and, Wasn't told that there was a possibility the car still wouldn'tt start. My question is can they legally force me to pay. The car has 1110,000 miles on it. a 1998 plymouth voyager I am not going to bother trying to put another engine in it. Please help me I'm not sure of my rights! Oh it would cost me 374.00 labor for the job