How to remove internal mirror plastic housing?

Hi there!

Can anyone help me a bit to remove interior mirror housing?

I've gone this far:
Attachment 38001

after that that big piece is not coming off at all. Looks like it's pretty much done and should come off right away but I didn;t wanna put a lot of pressure, without understanding first.

According to the manual, it should be very easy to remove and done this way:
Attachment 38002
https://www.vwaudiforum.co.uk/forum/...AASUVORK5CYII=but I seem fail to release the clip(s) at point C, in the above picture. Any help would be very much appreciate.