Questions About My Car Troubles

Hello ppl,

I have the infamous Chevy Malibu 2000 LS. Since i purchase it ( four or five months ago), i have had to replace the head gasket, water pump, radiator hoses, the thermostat, cam sensor and oxygen sensor. Unfortunately, my car started overheating ( less than three weeks after the head gasket was replace) again. The symptoms are as follow: my car temperature meter will raise to half way after driving only for five or six minutes. Afterwards, the car temp meter will raise all the way up and starts malfunctioning by not accelerating any faster or/and stalls. The engine is not even hot at all but the temp meter raises completely. Not only does my car overheat but my interior heater does not blow hot air. Today, i had a diagnostic done on my car and the mechanic said to me the reason it over heats is because the head gaskets went bad yet no water/antifreeze has mixed with oil (i thought when gasket are blown, water seeps in and mixes with oil) thus i have to have the head gaskets replace. Also, he said Mat (circuit) sensor my have a faulty wire or is has gone bad (engine light on). Finally, he said that their is also a piston miss fire (engine light on) but that is could be resolve by a doing a tune-up.

My question is, does it make any sense what the mechanic told me regarding the problems i am having with my car? I forgot to ask him what was causing my heater not to work properly, what could it be? Finally, can it be something else beside the head gasket (very expensive)?

PS: He charge me $1,200 to fix the problems and i am not paying that because i payed 1,400 for the car.
Also, the only time antifreeze leaks out, its from the a hose that is connected to radiator tank (by the cap of the tank). That hose does not go anywhere in the engine.
Sorry about the miss interpretation. The mechanic QUOTED me on the repairs. No actual work has started nor agreed upon by me.