Anyway the S recently needed a MOT so I thought I'd get a few things sorted under the warranty while I was at my friendly local Audi dealer (Lomond Audi in Glasgow).
I listed the following three faults :
- My boot was constantly reporting itself as being open (which is a bit more serious than it sounds as the alarm won't arm with an open boot!)
- The climate control display was "flashing" and didn't store the temperature in the key fob.
- And lastly, one of my Oxygen sensors was acting up.
This consisted of a new boot latch, new heater control panel, and a new lambda (oxygen) sensor. I didn't actually get the costs I had to ask the (surly) receptionist how much it would've cost.
The whole thing was very smooth with zero hassle or fuss (well besides the usual Lomond grumpy service staff

I was actually a bit worried about whether they'd fix the oxygen sensor as I only noticed it via my VAG-COM, though on refection I think my car was running a bit rich as well.
Anyway, I'm well pleased!