+1 - I've had a good share of shoddy places mark my wheels before, fortunately they were all right on the top of the lip so couldnt see it unless investigating it.
For anyone in/near Slough - ProTyre are very good - they are a Pirelli Performance Centre, which means they are trusted to work on the best cars. They repaired a puncture to my 370z wheel with no marks on at all, even cleaned off all the gunk they use to get the tyre on