Changing Vauxhall Vectra (53 Reg) door mirror

I need to change the door mirror as it has been vandalised, have bought everything I need and feel confident in replacing the assembly - except. Which door panel(s) do I need to remove to access the remain 2 bolts that secure the mirror. The 3rd bolt is conveniently accessed via a little rubber bung in the door but the other 2 are behind the small triangular panel with a speaker and the top part of the door panel. Can anyone give some advice? Done it before? Is it a case of just pulling them off as there does not appear to be any screws or bolts, I guess they use these push in clips? I'd rather have some idea before ruining the doors! Grateful for any wisdom.