or try the battery trick... being you pull the positive and neg from the battery, touch them together, then refit pos then neg. Touching them causes every system in the car to fully drain and reboot fresh, may solve the problem.
I went to the dealership who investigated the problem. An hour later all I had was a black screen - no radio, no satnav etc. I have to make another appt. to get airbags replaced so will see if they can have another go then.