I just read your post and thought 'what are you on about, surely you already got heated mirrors on an FR',
but now after checking the Parkers
guide im now in disbelef to find that the later
Ibiza models actually don't have these. I thought they were standard kit.
If they've took them off the range completely then i suspect the wiring may now have been removed.
However I know the Golf mkIV has its heated mirrors controlled from the heated rear screen switch, so I would have thought that it would be possible to do the same on the
ibiza. It may require the changing of a relay under the daah and putting the wiring in to the mirrors but I can't see why it couldn't be done.