Hi dave. I have an Astra mk4 on an S plate and if you open the door you will see a triangular plastic cover that the manual lever goes through. If you pop that off with a screw driver you should find 3 philips screws behind cover, just undo them and the mirror will just slide out of the 3 holes. Re-fitting is just the opposite of removal. Should take no more than 15 minutes.
Whitevanman1
November 2007