Heating cutting off for no reason?

My central heating keeps cutting itself off, a red light comes on and flashes on the boiler and i have to reset this to get the pilot to light and the boiler to start up, Scottish Hyrdo hve been out to look at this and could not recreate the fault but for some reason advised that my system may need power flushed as they could stick a magnet onto one of the pipes beside the boiler, they left and the problem is still persiting any ideas???