Have i missed the boat or something?? The Fix has already been stated several times to you Andrew.
Tell the dealer to replace Cambelt and cambelt tensioner to cure this squeeling noise
If you follow PDT's advise, you will have an expensive repair bill for no reason.
Er, thanks Steve, but if you follow the thread of the conversation two possible solutions have been posted. Some people have found the problem to be with the cambelt, others have found it to be the aux belt. As the noise seems to be coming directly from the aux belt it's not unreasonable to consider it might be that. Anyway, the cars having a cambelt replacement anyway so hopefully it will be that, and if not then I have some other starting points.
But thanks for your invaluable help, you're a star