First off - I did not buy my 04 CTS from Alderman, but it was under factory warrentee when I started going to them. Almost every problem - the answer is "that is the way it works". When I had no heat in the winter - they said it was cause I shut the A/C compressor off - after several trips they replaced the control module and it was fine. They left the Interior panels off, left the computer connector loose, so my feet get hooked on it. I have repeatedly brought it in for a transmission condition, and while they say they see it, are unable to get rid of the delay engaging in gear when putting it in drive. It took two weeks waiting for a part to get the signal light working (at least I had a loaner car).
They may not be able to fix much but they do wash the car. They also send a note after each service explaining how to fill out the GM service evaluation. They tell you explicitly to say that service was excellant.