[waynne]

I see now. On some cars if you push the vent fully up (or down) you can see a release clip or hidden screw. On vauxhalls you push the vent fully up then pull and the grill comes out giving access to the release screw. On other cars you need to insert a blade down one side to release the retaining clip holding it in.

It is really unusual for vents to be permenantly fixed - it must come out somehow. You could visit a breakers yard and yank one out to see how it is fitted. (Don't just yank yours out or you risk breaking the clip).