Try surgical spirit (from chemists) (it used to work for me) apply gently with a cleaning cloth(no water) (like a Jiffycloth or somesuch). Alternatively sprinkle plain white flour and wipe of gently with a damp sponge. I think there is a proprietry brushed s-s cleaner on the market, but can't think of its name. Good luck
i use Squireteco, made by Ecover, available in most supermarkets, sprayed on and wiped off with plain white kitchen roll.
I was told, but have never tried it because I don't like the smell, that after cleaning brushed stainless steel, you can protect the surface by wiping on a small amount of baby oil.