And it did not occur to you to disconnect the siren? :D

I don’t know what country you are from and what you use but you are extremely overestimating the level of complexity of these “security devices”.

Everything is clearly described in installation and service manuals. Everything is available from the manufacturer. You can install these systems DIY if you’d like. Disconnection of a sensor is a security event which triggers alarm no matter if it was armed or not. How to handle this is described in manual. The shitty support that couldn’t handle it speaks volumes about their competence.

The service codes which should be unique to each client and installation are reused on every system that given contractor installs. After a brief gig my brother had as a technician, he knew service codes for all banks and jeweleries in the radius of 150km… That disarms the alarm at wish and can modify settings :)

And you are worried that you might compromise the security by DIYing it? :)