Simon - thank you!! Saved me £130.
Get the part and do it yourselves folks. I a completely hopeless at anything in any way technical and I managed it in a couple of minutes. Do NOT put it in the garage. Also just don’t drive it as soon as you get the error message - really not worth the risk.
I would suggest getting the part from Audi if you can as I had a hell of a time with an online parts company who turned out were based in Germany and I waited over a week and it still wasn’t shipped. With shipping etc the part direct from Audi was £7 more expensive. Not worth the hassle.
An easy fix even for the utterly gormless like myself!