Interestingly, the Audi UK website doesn't list Swindon as the location of an official 'Audi Centre'. The nearest to you (23 miles from central Devizes) is given as Bath Audi. Perhaps it might be worth giving them a call? (01761 438300).
Possibly a better bet though might be to try the Audi VW Centre, just down the road from you (5 miles or so), in Chippenham. They're not listed on the Audi UK website but their prices look competitive to me:
https://www.audivwcentre-chippenham.co.uk/service