e133 fault baxi combi duo tec 28hea?

another e133 bolier fault,
ive no boiler light for the flame showing , tryed resetting, , lights work for the water and radiators and boiler clicks but not gas seems to be lighting , had a gas engineer come out yesterday said fan was possibly on its way out (2year old boiler) thing is we never had any issiuses until they re fitted the outside gas flue pipe (due to external work on the house), and alterd some copper piping outside)yet gas man said its nothing wrong with them , so cold , and been told we have to wait nearly a dam week ,if anyone has any ideas , why or what i can try to get the boiler to fire
i carnt see any frozern pipes etc and i also wrapped them with insulation ,