Had mine done ATS, KwikFit and, last time, by Audi. It works well.
Audi prices are not that far off the independents plus they do a bacteria killing thing, to clean out the airways, while they are at it.
This is the first I've heard about a specific lube being required.
It's worth remembering that you can always haggle (negotiate in Audi speak) with the Audi service dept
