Well, the noise coming from mine is the mechanical one!
I got VW Assist to check it out this afternoon and the mechanic diagnosed a faulty valve that regulates the air flow to the turbo charger. This is a fifteen minute job (but he did not have the part, which is sealed and not serviceable). So he asked me to check with Alan Day of New Southgate when I can get it done but I was told that, since it was a luxury car, it will have to be in for two days!!
After a phone call, the mechanic said he's managed to get the part and will come and change it for me tomorrow midmorning. I have to say I have been very impressed with VW Assist and in particular the mechanic - his name is Mark. He was so helpful. Hope the whole thing will be resolved tomorrow. As has been written so many times here, pity that the dealers do not treat their customers as they should and pity that VW cannot put pressure on them to get their act together or else remove their franchise.
Maxime