I have had a fairly good conversation with main dealer (service manager) where they seem genuinely quite concerned that such a small millage car 2019 model, looking to see if Audi themselves will pick up on the issue. Bottom line the diagnostic scan at 200 euro can tell no more than the scan I did myself. (i.e Ad blue ecu not responding to scan and Adblue quality below recommended urea quality. posted 6th Nov car was taken to main dealer on 7th) It looks like when these problems occur Audi has no idea themselves as to the final issues, hence the reason to continue replacing parts until the problem is solved. Of course with this procedure, I can do same in my own garage without the costs of main dealer ramp. I guess my main concern now is I no longer have faith in the Ad Blue system, and would no longer feel comfortable taking this car on any form of long journey as this issue may re appear, and the fact I have a countdown until the car will not restart! This is purely an emissions problem, and does not affect the reliability of what is a fantastic engine. Of course not being able to start this engine or have a current work around is now my issue. My options are now sell the car for a petrol Audi, or carry around spare parts for the Ad Blue with the knowledge of how to replace them.