vokera maxin 24e?

Help please, our boiler has stopped working, the orange light on the front of the boiler will not light up so we can not restart it I have had an engineer from work out to check all the electrics are ok, he says they are fine, no fuses gone supply ok to gas valve ok, he thinks it maybe the gas valve but he is not sure.
So before I go spend £100 on a gas valve could anyone help