I was main dealer through and through for servicing on my previous A4. But only did this as I knew about an ongoing issue with the oil consumption in the 2.0TFSI engine. The pistons were made of chocolate and required 5k worth of work to fix. Audi UK covered the cost by way of "good will" for having main dealer stamps so there is an argument if something serious goes wrong you would get help from Audi UK... It's a lottery though...
I came to trade in my A4 against an RSQ3 and they offered me a paltry part ex even with FASH. Sales guy said it was a fair offer and would go straight to the auction, "we wouldn't make anything on it". I went elswhere and sold to an independent garage for 2k more than what Audi offered... So FASH didn't mean squat to them at trade in.
So I've since found a really good Indy for my RSQ3. They still use genuine oem parts and have access to Audi service database so eveything is still on order.
Just had major service/oil change, haldex changed/filter cleaned, even took pics to show the state of it for me. Audi don't even recognise the haldex filter as a service item, they just change the oil!
Go for a good Indy mate, they take pride and you'll save a fortune in labour rates over the years!