Hi,
We had this happen to our previous
MCS and it can happen at high speeds - went when I was driving at about 70mph down a duel carrigeway. Our's was fixed under warrenty and they changed the pump - then within 24hours it had gone again. Turns out it was the power steering control box and the connectors. These were then replaced and had no further problems.
Don't know if this helps
All the best in getting it fixed
Andy
