2006 Vauxhall Zafira rear passanger door won't open

I am assuming that your zafira has centeral locking and would reccomend checking that the lock is actualy operating on that door.Try to listen for the lock operating when the centeral locking is operated. If it is then I would think that you have a issue with the connecting rods from the inside and outside handles (would be highly unlikely).

hit it with a big hammer