Hi mate and welcome to the site. Its a common complaint of the estate and it usually always points towards a broken rear glass break sensor wire which is also the rear demister strip. Does your rear demister work properly? Have a good look at the track and check for any cuts is the ribbon thats attached to the rear screen. The power sounder is very quiet in the vec and is located in the right hand boot cubby next to the REC. If you unplug the power sounder the the cars horn takes over as the alarm but this triggers the "safeguard" Is your alarm coming from the power sounder or the cars horn?
The ultrasonic wiring can also become detached (up by the rear view mirror), this will also trigger the safeguard and set the alarm off. To check its plugged in properly you need to drop the courtesy light panel, unclip the ultrasonic panel, then unclip the light lense and take out the 3 screw, push in the tangs and the light assembly should drop out. The ultrasonics are plugged in there.
In short the warning "safeguard" is a fault in the alarm system.
Hope that helps
Steve 🙂