Ben, firstly, thanks for your reply, its posts like yours that are going to save me a packet other than rushing into it and saying to a garage 'yeah, send the turbo away etc etc'.
I have been told its one or the other, they said it was a carbon build up in the actuator or the turbo nozzels and they need cleaning. Whatever they did with this hand vacuum on the actuator made it better, so like you say, it needs taking off and or replacing. Are they defo available as a spare part?
It seems ridiculous to me that VW produce a part that when it gets 'dirty' then its going to cost £500 to clean. Serioulsy, what kind of an outfit are they?
I've had it with VW after this, my Golf has cost me so much in repairs, its becoming a joke.
I'm based in Staffordshire.
Cheers mate.