Alarm going off
 

Hi
Audi A5 Quattro 2011. The alarm has been going off randomly. The orange indicators are not going off, its not what the normal alarm sounds like, its like a high pitched beeping for a while and then it goes off.
I have no warning lights on the dash, and the car is running without issue to my knowledge anyway.
Ive rang Audi and of course they want €150 euro just for a diagnostic.
Anyone any advice on what the issue could be or how i can sort it myself (well, get someone who knows about cars to do it for me, LOL).

Any advice would be much appreciated