Now do not laugh at this.
Last week my power steering stopped working after I had got myself stuck in the snow,miggys must be the worse car ever made for driving in snow.
But anyhow after checking everything out fuse fluid drive belts etc,a neighbour told me that his astra had suffered the the same problem a while ago,and he had traced it to a poor condition battery,rechare the battery and hey pesto problem solved.
Now i thought what a lot of balls,but next day another friend also told me much the same story only with his combo van.
So with nothing to lose,I charged the battery ,restarted the car and the steering worked perfect.
So before you spend any money,make sure your battery is in tip top condition,as the engine managerment computer seems to want to shut down unnessesary systems to safeguard itself.
My own battery had a few dud cells,so its worth a try isn,t it .
Best luck Alfie.
ps its true it really did work.