Hi Liam, Yes I had exactly the same problem and finished up replacing the turbo. The warranty outfit refused to pay out as they said there was signs of carbon in the turbo. After some words with the garage that I bought the car from, as I had only had the car for a few weeks. The garage were very good and paid for the new turbo. This was all 20,000 miles ago and not had any problem since. My car has now done 112,000 miles and I love it.
Cheers
Rod