Well I picked up the car today. I have a piece of paper that says they washed and vac'd the car (they didn't, under my instruction - should they be charging VW for work they haven't done?), It also states that they carried out a full ACC recalibration and tested - all ok.
So I'm driving home, happy that I have my R back - for the first few miles the steering seemed really heavy (compared to the Fabia). I put my foot down a bit, saw that the <car>!<car> white warning seemed to be on more than it used to be, but still seemed inconsistent (I could follow a car, see the warning come up, and then see it disappear again without a change in direction or it getting any further away from me). Sure enough, when exiting the Tyne tunnel I get that familiar warning that the sensor has a limited view.
Same fault. So they recalibrated a buggered ACC unit. Will be on the phone to them tomorrow to discuss them getting a replacement sensor sanctioned.
If they did the work the paperwork says they did, I should at least have assurance that my 4 wheels are perfectly aligned.