If they are a plumber and a sparkie,then they must be rubbish. :

I don't know any plumbers or sparks that would even have time to contemplate trying to do carpet cleaning as well,and they would be earning more per hour than carpet cleaning taking into account markup on materials/parts etc.
CCs can usually fit a job in pretty quickly,try phoning a plumber and ask him to do a job at short notice and he will probably laugh at you.John