Extremely disappointed after purchasing certified ...

Extremely disappointed after purchasing certified pre owned 535i from Devon BMW. They claim that certified pre owned goes through series of service and detailing before it goes for sale. Not even a week i started driving the car, the AC stopped working. Also, I had to bring back the car for a stain in the dashboard and a dirty seat belt. My biggest disappointment is the AC. Seems like the dealership just want to get rid of the car without being properly checked. I will definitely not going there for next purchase and will not recommend others to purchase any pre owned cars from there.