Did you have any luck sorting this out. Mine did the same on my 14 XV diesel back in January but after restarting it was fine. However over the last couple of weeks it has done the same as yours regularly and today I have tried to restart about a dozen times and its not resetting at all. Every time after about 5 seconds i get the 'clunk' and the warning light and no power steering. Hoping that there is an easy fix to this as I'm thinking otherwise it sounds expensive 😞