I bought the car in Dec when it was cold so we did not turn on the air conditioner until we went to Fl. in Jan. Noticied a loud rattle noise when ever the fan was on. I took it in when we returned to MD in April and they said a new compresser was needed.They replaced it and changed the oil. After picking up the car and drove 1 mile the red oil pressure light went on and a loud ding started and would not stop. They have had the car for several days and can't stop the problem. They have been on the phone/computer with Detroit and still haven't fixed it. We have had Buicks for years and to have these problems with only a few thousand miles on it is extremely upsetting. AND THEY DON'T KNOW HOW TO FIX IT!!!!!!!!!!! What do I do?