A4 B8 driver side vent slider/tab fell out - advice needed

[cashutt]

The tab used to adjust the vent on the driver side fell out this weekend. I got the two parts out of the vent and worked out how they clip together. But I can’t work out how to clip them together while inside the vent, I’ve tried using pliers though the flaps of the vent, but it’s too complex to clip them together with pliers. Has anyone fitted one of these before?

I took a couple of photos

its a 2008 A4 Avant.

Any help would be much appreciated!