I'd like to recommend:
I had a problem with stuttering at speed and had it in at my dealer (where I bought the car). After they had completed the 54,000 mile service(at 52,000) and passed it on an MOT they suggested it might be an intercooler problem. Said it would take £180 and 2 hours to investigate.
I went to book it it but they said they were booked for a month so I booked it into Wm Goss in Ireland.
The engineer took the car for a test drive, then flicked up some clips to remove the front grill. He showed me that the intercooler was deformed and would need replacing as it was certain to go soon.
They did this the day after and showed me the intercooler where it also had a hole in it! The car now runs great!
They were very helpful, considerate and informative.