Hi Gareth,
Thanks for the reply. My name is Nick, can't see anywhere under profile settings where you enter this.
Anyway, I dropped into a local body shop today (no where near the dealer, I am 100 miles away from them).
He confirmed a few things for me. Nothing has been resprayed as far as he can see, he checked and compared all of the door panels.
He thinks it will have been a stone chip and also thinks the bubble has been there for some time as it is quite hard to the touch. To repair it properly, will involve spraying both door panels, circa £400. Or just flick the bubbled paint off, check no lasting damage underneath and touch it up.
Meanwhile I have spoken to Audi today and provided them with the info I got. It is being checked with the 'used car manager' and they are getting back to me.
Will keep you posted.
Nick