This is the worst car I ever had, it was nothing but problems since I drove it out of the dealership.
At 10 miles the passenger side mirror fell off the car.
At 25 miles the brakes were soft and had to be replaced.
At 170 miles the transmission was replaced.
At 194 miles the tires had to be replaced.
At 200 miles the idler arm was replaced.
At 275 miles the engine was replaced.
At 400 miles the radiator was replaced.
At 560 miles the shocks/struts were replaced.
At 735 miles the power seats broke and were replaced.
At 750 miles another transmission was installed.
At 1,000 miles I put a for sale sign in the window.
This truck was a serious lemon, it was in the dealer for service more than I drove it. I called GM headquarters with my list of problems and they were not very helpful, they wouldn't even authorize a loaner car for me! I would never buy or recommend a GM automobile.
You should have taken it back and declared it under the "Lemon Law." If it qualified (which it sounds like it did) the dealership HAS to buy it back. I reccomend you do that if you still have it.