Get them to look at the ignition barrel wires/solder joints. Get yourself the Eastern Beaver relay mod kit & fit that when the shop has fixed the bike.. even if it's NOT this problem, unless you do the relay mod, it's gonna let you down sometime. ( easy to do , circa 60- 90 mins work, dependant on how many beers ya drink whilst doing it!)( Atomsplitter did a write up on it which Eastern Beaver used for their instructions!)