Humidity / Air quality sensor box cover

I have the black plastic box on the windscreen for my air quality sensor but the cover has been cracked, replacement cover has been found but yet to order as I cannot get the old cover off, has anyone had this off before and can tell me how to do it.

Pics?

I believe it just pulls off.. but there is a video of a guy changing the windscreen of the Evoque on YouTube, where he removes all this stuff.. might be worth trying to find that and see if it gives some clues.