It's obvious that you have a current draw problem which is draining the battery. I have been through this a couple of times w/ the wife's G35 (battery conservation circuit was disabled), and my 83 MB 380SL w/ a bad radio antenna killing the battery. Service departments despise electrical problems because they are time consuming and require some intelligence to diagnose. Do not take the car back from the shop until the electrical system, including the radio, is completely checked out by someone who knows how to do this and is familar w/ the car's wiring. I doubt this is a lemon type problem, but the incompetence a/o laziness of your service department may result in a lemon declaration. I'd have thought Brumos would be of better calibre.