Question Author
Methyl - Was asked if I wanted it washing and accepted because the 2 garages I'd called in to wash the car had broken washers.
Zacs - I don't think it's changed to KPH as even going slowly, the speedometer was showing that I was travelling very fast. When I came to a speed camera and slowed down to what my car said was 30 mph, I was crawling long. I think the bloke behind me thought I was crackers.
Anyway, I'll check tomorrow. Just wondered if anyone knew if the person who did the airbag could have somehow inadvertently done something to the speedometer.
Thanks for your replies.