It's the colour coded shell plus the black housing that surrounds the shell and holds it in place. The black arm holding the mirror unit to the door is fine, as are the electrics.
So I guess I will need to remove the entire mirror from the door, somehow get the old cracked housing off the arm, replace it with the new housing, replace the colour coded shell and the indicator lense + bulb.
I have ordered the parts so can give you the part numbers if this helps?
If you have a diagram showing how to remove and refit this would also be very useful. I found one on Just Answer but it was for the older shape Jazz/Fit and the mounting + mirror housing is completely different (mine is an '09 model)