They may offer to repair it, but the chances are they will try to get a smart repair outfit to do it for £40. You know, I know, everyone knows that diamond cut wheels can't be repaired in the back of a van with some filler and a squirt of silver/chrome paint.
Lepson charge around £80 from memory to do a first class refurb, but it would mean being without the wheel for a few days.
For future reference as others have said, some dealers have fitting machines designed for fitting tyres on larger, delicate wheels. I do a 60 miles round trip for my tyres as I have found a dealer that I can trust 100%.