Hi DaroB,
TSB (Audi America) 37 07 07 201302/3 dated 13 Apr 2007 supersedes TSB Group 37 Number07-01 dated 18 Jan 2007. My upgrade was done at Audi Northampton in Aug 2009. I think that the UK TSB may be 2009736/7. The Master Tech was Nigel Bushnell and when I spoke to him last Sep on another matter he remembered doing the flush, fluid change, software upgrade and adaptation. I suggest you get your dealer to speak to him. It completely cured my problem and the car worked perfectly until I sold it in Sep 2013. Be warned the job is not cheap - in Aug 2009 the bill came to £736 of which more than half was the very expensive "Blue Fluid" (16 litres). I now have a D4 4.2 TDi which is even quicker and more economical (quicker than my Porsche 911 Carrera 4 to 60 mph!). Sorry about the delay - I do not check this forum very often because there are so few A8 posts. If you google "A8 hooting noise" you should find some references.