I have a 2007 56 plate GTI (UK) with Factory Fitted Parking Sensors and Highline Computer with Highline CCM.
My mirror dips but have noticed that it only does it with one of the keys so I guess I need to set it up with the other one.
Instructions I got from another site:
1. put it in reverse
2. put mirror in L position
3. adjust mirror to see curb
4. take it out of L position
5. take out of reverse
(4 + 5 may work other way round)
Not tried it myself as was already set up with one of the keys but will give it a go with the other one.