2003 Oldsmobile Alero Car Won't Start?

I had my car towed to the local auto mechanic because it would turn over, but wouldn't start. The mechanic said it was the computer system. $800 later I drove the car home. 2 days later I went to start the car in the garage and again, same issue and had to get it towed back to the same person. He said that it was the security issue with the computer because it wasn't program correctly. 1 week later, driving down the road, it quite again, and had to coast into the gas station. I got it towed back to the same mechanic and this time he said it was the Fuel Pump. Its been 2 weeks since that incident. Yesterday I left my car sit until today, when I got back to town, same issue, it won't start. What is going on with my car. Is this mechanic just screwing me over? I need some answers soon.