M3 / 2002 - How to disconnect the alarm system

[Torexplo]

Hi,
My problem: I believe the alarm system of my 2002 M3S has been giving me troubles for a while. A few years ago, when sitting in the parking garage (locked one time with the remote key) it randomly turned on the alarm (sound and lights flashing). More recently it randomly starts to flash the lights but no sound anymore. However, this issue has been continuously draining my battery and after 3 to 5 weeks I have to jump start it as the battery is completely empty.

Technicians in Switzerland are not familiar with my US model (bought new, at Moritz BMW in Arlington TX back in 2002). Swiss technicians have tried to program the system that the alarm should no longer turn on but it was not successful.

Anyone familiar with how the alarm system in my M3 US model can be completely shut off? Disconnected? It looks like if I leave my car unlocked, the problem does not occur. They don't know how to do it over here.

Thank you.
Maya