Car Alarm going off randomly

[morganash]

Hi, I read another post about Alarm problems on here and replies suggested it was a split rear washer hose. My car is a 2014 b7 estate and until the other day I'd never had any issues with the Alarm sounding - Until I had a full service and they tested and found my rear washer was not working - which it never had since I bought it. But it seems a coincidence that hours after my service this problem started... I rang them but they are too busy to look at it.
So today I took the tailgate panel off and everything looked fine, there was no water on or around the tailgate latch or rear wiper assembly, all looked like new So that rules the split hose theory out as a cause I think?. I checked the headliner at the back and could see a blue line, which shows why the washer doesn't work, as it has split in the roof space. Can I assume that leakage there is not the cause of the malfunctioning alarm? as there are no electrics in the headliner to be compromised?
One strange thing on the way back from garage was a whirring noise coming from the tailgate area - like a small motor that was stuck on? It eventually stopped, and hasn't sounded again.
I've since bought a new stop/start battery incase that was the issue, but it made no difference. I'm currently leaving the car unlocked so as to stop the alarm waking all my neighbors.
Can anyone suggest any other possible causes? Thanks