how can i fix my vauxhall astra key fob?

The key will have to be linked to the car using diagnostics such as Tech 2, Op-Com etc.
You will need the security code, which is on your "car pass" card.
Remember to transfer the immobiliser chip from the old key to the new one, as they cannot be re-programmed.
Buying keys from ebay is usually a total waste of money.
Good websites are-
www.vauxhallownersnetwork.co.uk

www.vvoc.com

ken
April 2010

Google Vauxhall forum and ask there (not being funny, they'll know best)

Simon
April 2010