We have those floors too. I use something called Pflege Wachs (Saicos Coating Systems). It seems to get the stains out pretty well. There's another product by this company- I think it's some kind of Seife for daily use (can't remember the exact name as I ran out of it). Anyways, I got it at this place in Dietikon- they have a website though I haven't had a look at it-
www.balteschwiler.ch. Don't know if it's exclusive to this wood flooring store or not. We also rented a machine there for more intensive cleaning.
I don't think it's such a good idea to sand the floors- they're not thick wood like the kind of hardwood floors you might know from North America. Here, it's really just a thin layer. You can get some floor boards replaced (expensive though)- but a certain amount of wear and tear is surely acceptable from a rented apartment.