faulty clifford matrix rsx 2.5

alright, ive been having problems with my clifford matrix rsx2.5 thats installed in my 2000 vW passat (5spd). no remote start installed. The problem is that the alarm goes off every 1 hr 15 mins after it is armed and it says its because of the door sensor. I took it into the shop where i had it installed and they told me it likely had to do with a relay for the door pin. he changed the way it was wired and its still doing it. im out of the warranty period now. im assuming it is the brain unit because i know after a little while they can go bad and have problems. What i want to do is either fix the problem or switch out the brain unit. The problem is i cant find any 2.5 units to buy. what other DEI security system would i be able to put in there and still keep the same wires. im confortable working around in my dash i just really dont want to rewire everything if at all possible. thanks

Maybe a simple diode in line on the door trigger wire....?