Thanks Mark,
I think your last route is probably the most practical, unless you want to get into Small Claims Court cases with the dealer and/or Audi U.K. If you did want to do that, then you would obviously need to ‘invest’ in qualified and professional reports and representation at court.
Of course, the ‘contaminated’ coolant possibility, is indeed just that, and the heater core may not be blocked/partially blocked as a result, and the non functional heater may be a heater control malfunction.
I would check the small print of the warranty ( who’s warranty is it?) before deciding anything, since they - not the Audi dealer, or Audi U.K. - are the deciders of what is covered or not.
Kind regards,
Gareth.