easy way is to remove it and take to a vauxhall garage for repair , if you can't do it yourself they will remove and fix but when did mine was around £80 (they can repair lock or replace with a new one , if repair is cheaper)
when i did remove it myself on a different car was a few pound as got some locks of ebay and fitted myself
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.