Ok... UPDATE TIME!
The car went into Brighton Audi this morning for a proper diagnosis and at about half 4 this afternoon i got the verdict....
Unfortunately, although there is some play in the viscous fan coupling, this is not the cause of the overheating. The water pump has packed up! apparently the fins of the drive wheel thing have collapsed

and also the thermostat is intermittently at fault. Ok, big problem. I asked the guy what the costs of this job would be and had he been able to get in touch with the RAC Warranty people to confirm that the work can be done under warranty claim. He said he hadn't been able to get hold of the warranty people but would keep trying. in the mean time, he passed on the costs to me ... to replace the water pump and thermostat, inc parts and labour and everything.... £890 !!! .... Ouch. So i check out some more contact numbers for the warranty people and pass on another number for the guy. He also mentioned that although not failed, the fan coupling wasn't totally right and could cause problems if it fails later and that now would be an ideal time to replace the viscous fan coupling as i wouldnt need to pay any extra labour. So i say to go ahead with that too.
He rings me back having spoken to the warranty people... mixed news. Yes the water pump / thermostat is covered, no problem there but as per the policy wording, they only pay the first 25 quid/hour of labour. and infortunately its the labour thats the lion's share of the cost of the job. so the RAC will indeed stump up for the parts and some of the labour but i'm gonna have to fork out £580 for labour (including the viscous fan bits as this isnt a warranty-able)
so, the work is going ahead as i need my motor back, but i'm still gonna have to whack best part of a grand on the credit card and then only get a few hundred back from the warranty

... deffinitely going to be some choice words put into a letter to Audi HQ and Audi Worthing about the shocking service, and fact that they failed completely to spot that a waterpump and thermostat was failing / failed. whether its their direct fault or not, they should have spotted this and a couple of other minor things the brighton techs told me about.
Should hopefully get the car back tomorrow eve or friday. In the mean time, the spanking new A3 2.0 TDi Sportback they gave me to run around in is actually proving to be bloody good fun

was most pleasantly surpised with this, especialy when having done 50 miles this eve i find the computer telling me i still have 500+ miles left in the tank
