I thank you all for the expert and quick replies. It surely cleared my doubts about this shop's knowledge on MB's and avoided them from inflicting any damage to my car. I totally agree that this hit or miss "bonehead" like speedy said will disable the factory alarm and possibly create more problems. Now its time for me to shop around in the SD area for a legit MB alarm installer or would have to do it myself(which I tried to avoid because of my busy sked). Any suggestions is more than welcome.