Are you getting it done under warranty?
If not, when I asked for recommendations re a rebuild Johnny Boxer mentioned:
Quote"I reckon Steve @ Scrimmager is the man
http://www.scriminger.co.uk/10380/info.php?p=1&pno=0
They are one of the best BMW engineers in the UK"
....near to you I think.
If not Roy at RGM in Lancashire (links on here somewhere) offers a good service (I used him)
Good luck.............