I had that happen on a Chevy celebrity I had bought. Overheated and had to replace the head, head gasket, and water pump. Was in the shop 5 out of the 7 months I owned it. Also had an overheat on a Ford Focus I bought, the replaced the temp sending unit, the instrument cluster, and finally the head which was milled to shallow (out of specs) with a new one. This can happen to anyone, you just happen to be the unlucky one this time. I've had it happen to me twice now, so I know what you are going through. Just hang on, they will get it right.