Received the replacement window/mirror switch unit today, took around 20mins to fit it (the screw's were being very unhelpful). I now have working electric mirrors
So problem solved. I'm sort of glad I worked through this as I've not seen many posts across the interwebs which has this particular problem and hopefully might help someone else someday.
Thanks for you help Stoney. I'm toying with the idea to put a strip of LED's just under the upper lip of the luggage compartment for lighting but this is a while off before I do, I'll do a guide when I get round to it.