Had the same problem with my Zafira. It was the control cable that had come off at the back behind the heater. I got vauxhall to fix mine. Not too expensive. First of all they tried to re attach existing cable. This they did twice £20 odd but in the end relaced with new cable total £40 dd if I remember rightly. Wish they had replaced first off if you do take in insist on this if they say problem the same.
