My saloon alarm keeps going off completely at random - e.g. it can happen once in two weeks or several times in one day. It usually happens when the car is locked but it's also done it when the car is unlocked.
*** In all cases the key fob is nowhere near the car.
Once the alarm has gone off, pressing the unlock button on the fob, then the lock button, causes a
'something is open' single beep.
I've tried a 60-minute battery disconnect but it still happens.
*** I have to disconnect the battery every evening to be 100% sure it doesn't go off in the middle of the night.