The S-lines come with Brushed alluminum as a no-cost option in the S-line pack (as detailed in price list page 16/17). But you still need to spec it, even though its no-cost. (like the no-cost option climate control, who WOULDN'T have it?)
The web site is a marketing gimmick - generally unreliable.
Japper - the medial alu is real metal i'm sure. I had it on an A4 and kept denting it with my mobile phone round the gear stick / ashtray area! And it is cold like the door pulls etc. not warm like the plastics.
Medial is only availble on NON s-lines for £80. If you ordered (and paid) for medial with an s-line, then the dealer has kept your money and lied to you. Their computer ordering system would not allow medial + sline.
You can always argue the price before you take delivery. My dealer tried to charge me for DIS on a sport. I ordered the car at that price, but when I found out that it was standard I phoned them up and they said.... oh yeah, sorry, we'll knock that off the delivery price for you. Bet they wouldn't have if i hadn't queried it.