Car can be fine and starts without a hitch but then occasionally decides not to start after having stopped somewhere for a break. Engine is cranking and it's not possible to bump start the car by lifting the clutch so pretty sure battery is fine. Plugs recently changed. Mechanic couldn't diagnose and refused to believe it was fuel pump as car would cut out when running which it doesn't. Sometimes I wait 10mins and it miraculously starts again as if there was no problem. Bit frustrating really as you never know if it's going to play ball on not on any particular day. Help!!