I need some help. I don't know very much about cars. I have taken my car in four times because it has been overheating, and it still hasn't been fixed properly. The first time they replaced the thermostat. Then they replaced some sensor that tells the fan to come on. It was still broken, and they said it wasn't the water pump because it wasn't losing pressure. They said they didn't know what it was. So I took it somewhere else. They said it was a valve that was blocked or a valve that some older Chevy's were made without that didn't let air circulate properly. Then it was still broken. So the last time I took it in they said that the thermostat was hung. The first people didn't install it properly. So I got my car back yesterday all excited because I thought finally my car was going to be fixed. On the way to work this morning, it overheated. What is wrong? What could it be? And how I am supposed to find someone who can fix it right the first time?