No question - QST (Kim Collins) in Haywards Heath. Quick trip on the train of you don't have a spare car. Best service and save a fortune from the main stealers.
Let me know if you need their number or directions.
QST are very good and have an excellent working knowledge of older Audis too. Kim certainly used to offer a courtesy car if available. Some interesting beasts too - I borrowed a rather nice S2 Avant.
QST got me out of a real fix last year when my 100 S4 broke down for the first time (after five years - that's not bad) near Arundle. Audi UK wanted "at least nine weeks" to get it fixed. Kim did it in three days.
Dialynx are good too of course but they're a bit out of area.