Toad Alarm false triggering

I have just has a Toad C4 alarm fitted to my car and the system is
false triggering.

This is always caused by the ultrasonics (indicated by the number of
LED flashes when disarmed).

The alarm can go all night without triggering (parked in a locked
garage, on a driveway or in a car park), but when it *does* trigger it
usually goes off several times in a row (after disarming & re-arming).
What could be causing this?

Is there a way to adjust the sensitivity of the ultrasonics?

TIA
Andy

the ultrasonics usually had an adjustment screw on its control box. If this
is set to high then the alarm will be triggered sometimes for no reason.