This is what I am saying to you. You do not think an alarm with do anything? Once your alarm goes, it immobilises the engine. You need an atication sequence to tell your computer that you are the owner of the vehicle, so it releases the immobiliser.
But, if your mechanic thinks its the alarm module, then you can go with that. I have not seen it, so I don't know. All I know is when you replace the alarm module, or fix it, you will need a remote to activate and de-activate. Unless you remove the entire factory security system. Also you dorrlocks may not work, as part of the shutdoiwn sequence of your car.
I will leave this to you and the VW dealership. Good luck
**Working PART-TIME for Carjunky for a while, Please bare with me =)**