Thank you all for the valuable inputs
@C3PO it's a very small world, just read the service book and the car was purchased new from White Rose Volkswagen, Skipton Road, Keighley! I'm going to give Ben Smith a call and see what he says, no harm in trying listening to his sound advice.
@andygo thanks for the help offered. I would love to give this a go but I don't have the necessary knowledge and I live in London flat, so have parking space issues, although I have a VW dealer a few yards away....wonder if they'll allow me to use their garage
Out of curiosity how did your son manage to get his GTI sorted free of charge? Was it purchased through a dealer? Also as you said, my reason for not getting a warranty is that it's £500 and it kicks in only after I have an issue (plus diagnostic costs are not necessarily covered). And it's only for a year.
Nevertheless time to sort this out asap and for the car to sound less like a dirty diesel! And I thought VW's in general were solid!