Hi Gareth,
Thanks for this. I have started calling around independant dealers and will likely take the car back from Audi (they've not opened it up yet - it was a visual and camera inspection).
Its less that I'm used to big bills (although that might well be true), and more that we've been very lucky the car hasn't needed any engine work to date. Regular servicing/MOT/tyres etc was always independant dealers but not Audi specialists (eg Kwik Fit). This is the first time its having any significant engine work, hence was keen to get an audi opinion first. But as you say, i am discovering some very knowledgeable inpendant Audi specialists and the prices are considerably lower, so seems like its time for me to get to know one of them better.
As I said - I appreciate the advice - thank you
Zahir