Air Conditioner problems of the 2008 GMC Acadia

We purchased our 2008 Acadia in 2011, it had approximately 30,000 miles on it at the time of purchase. Less than thirty days after purchase we had to replace the front rotors. At 40,000 miles we had to replace the front brakes; the air conditioner backed up, which required maintenance to the blower motor; and the head lights went out, which required replacement. At 45,000 miles the rear struts went out, which required replacement; and we had to replace two tires. At 60,000 miles the water pump went out and needed to be replaced. At 55,000 miles the front struts went out, which needed replacing, along with four new tires, and a new set of headlights. At 60,000 miles the rear brakes and rotors needed to be replaced. At 70,000 miles the transmission went out, which also required replacement. The final incident happened on 6/10/13 at 74,000 miles, while I was driving with all three of my children. I was going 50 miles an hour on a highway, and the entire car shut down. The steering console locked with the keys in the ignition, I had no ability to steer the vehicle, the brakes did not function either. I had to use the parking brake to slow the vehicle down, barely avoiding a collision with another vehicle.