I finally got around to taking my 2010/2011 Audi A3 s-tronic 7-speed in for its gearbox service. I was referred to Friendly Motors in Goodwood. They changed the oil (R475 ex vat), mechatronic fluid (R650 ex vat) and labour was R900 (ex vat), the total came to R2328 vat inclusive. I was expecting a filter to be changed but they said for the 7-speed there's no filter to change, but if it was the 6-speed then that would have been the case plus a lot more oil required (2 grand alone for the oil). They said there weren't any issues, the gearbox works well as it should. Prior to taking it in I can't say that I noticed any issues. Hopefully I'm all good still for many more years to come.
My mileage is now 117,500km, this might have been the first ever gearbox service but in any event I was way overdue. I dont see any record of the Audi dealerships I serviced the car at having done one, though they did replace the clutch pack in September 2013, I dont know if that would have involved an s-tronic oil change.
Edit: I would recommend them based on them living up to their name and being indeed quite friendly seemingly very knowledgeable

Father and son owned business and they were quite happy to show me around a couple of the gearboxes being worked on and explaining things to me, not that I absorbed it all