Its tough to do because it is a multistage paint. A place like S&P will want the finish to be perfect, so will want to strip the wheel and start again, hence why I said they'd be expensive and take ages (I should have been more specific).
Any SMART repair place may take it on, but wont get a perfect colour match or repair, but may get it close enough. You can always try Wicked Wheels. I think they are a franchise so only as good as the one you visit.
If you were near Basingstoke, I'd recommend My Alloys, they are very good, and used to run a Chips Away franchise, so know how to do SMART repair, so may have been able to do something, dont know if they would tackle it though.