Get yourself a cut throat razor blade.
Scrape the seats with a small amount of pressure and it will scrape the 'fluff' off.
Give them a clean with some good quality cleaner and bob's your monkhouse.
Cheers pal, what seat cleaner you think i should use? I got some AutoGlym Interior Shampoo..
That's 'ok' on alcantara but I'd try a dedicated alcantara cleaner. I find the AG stuff leaves the Alcantara a little stiff for my liking.
Something like Race Glaze gets good reviews.