Seat need to sort this out. When I bought my ex-demo car I commented that the dipping mirror didn't work on the test drive - the dealer told me it probably hadn't been switched on in the menu. Looks like he either didn't have a clue or was telling me a load of bull.
Either way, we know that it's possible to have it retro-fitted, and Seat need to be doing this as a good will gesture. I think I need to write to their CS again.