Whenever our car sits and during the cold winter months, we get a message that reads "Low battery - no convenience functions" - i.e., heat, wipers, windows, etc. Can this feature be programmed out of the vehicle?
Convenience Options on 2006 Mercedes-Benz CLS500
I have the same car as you, and did have the same problem, after taking it back the MB dealer, they changed & checked all sorts of electrical stuff, they found out it was a 'bad battery' it was replaced and I have not had this problem since.
The convenience options are disabled when your battery is too low on charge. after driving for a while, you will notice that they should return. This is primarily due to the alternator charging the battery to proper specs. Two possibilities here. The factory alarm is draining your battery and if you are planning on leaving it in the garage for extended periods of time. the other possibility is that your charging system (he alternator) might be on its way out. If you test the battery after driving the car and the convenience functions have returned, it should hold 12v when a load is placed on it. If it does not, then it might be a bad battery as well.