I've had a few alarm related problems over the years on my mk5's.
The main culprit is usually the internal battery of the alarm siren self combusting, so it needs a new siren.
Last time, it was a new battery needed and the alarm was going off due to dropped voltages.
It has also been known for ultrasonic sensors to cause issue.
In 46-CCM, if you look at measuring blocks, it will tell you the last few triggers for the alarm, this will point exactlky at what you need to replace.