Rob - Kwik-Fit Mobile have repaired my run-flats twice - once was a Goodyear, the other was a Pirelli - it was through my works account but the dude never even batted an eye-lid that it was a run-flat tyre try 0800 425262. Otherwise try a single trader tyre dealer.

Finally I also once got a nail in a location that they wouldn't sort - got all 4 tyres filled with tyresafe for £30 and never had to top the tyre up again till it was time to replace them!