Air Brake Related Problems of the 2002 Chevrolet Cavalier

Air Brake Antilock problem

Aug 31 2002, purchased vehicle. December 5, 2002: abs activated - lost brake power, sailed through red light. Abs activated on dry pavement in garage, no deceleration, used emergency brake to prevent collision with back wall of garage. December 9, 2002: took the vehicle to the dealership/ mechanic and manager drove the vehicle. Said abs was functioning properly. January 21, 2003: brakes failed causing rear-end colllision. Airbags didnt deploy $5,000 worth of damage to front end - less that 4000 miles on veh. Contacted GMC, explained events . GMC investigator downloaded data from abs/air bag device. From that information alone, GMC determined nothing wrong with brakes without driving it -undrivable damage. I received a copy of this print out. Immediately upon getting my vehicle back from the repair shop, I notice vehicle shakes violently when brakes are applied. Repair mech states he didnt touch the brakes - wasnt accident related. Dealership blamed the brake problems on the accident even after repair mech told them directly it wasnt. Dealer turned my rotors and replaced the left wheel bearing which was broken. I still have consistant problems with the abs -activates for no reason/doesnt activate when it is supposed to/when activated it doesnt slow the car down/when activates -all brake power is gone. The left front tire locks up and skids regularly when braking but abs doesnt activate. An independant mech pointed out the dealership had turned my rotors to a point beyond the "machine to" and they failed to sand the rotors which was causing the horrible grinding. I spoke with the dealership general and maintenance managers. We all observed remeasuring of the rotors then they replaced them thin*. Managers stated they didnt know anything about "machine to" specifications and they told me they dont sand rotors after turning them. Untrue: the second time they turned them, they did sand them .