[Munger2k]

My E93 has a god awful rattling coming from what I assume is an air vent between the rear headrests.
I've searched the forum and have found many threads about a "rear deck rattle" but this isn't that.
I've also taken a look at how to remove the offending vent so I can pad it to remove the rattle but either I'm missing something obvious or it doesn't look like it wants to come out and I really don't want to end up snapping something.
Can anybody point me in the right direction to get it out?

P.S. this is my first post so please be gentle!