Question:
i got a big square brush thing as well but it doesn't work that well ...

Answer:
I don't think the square brush cleaning thing works very well either and usually clean mine by wetting it under the tap then shampooing the bristles (being very careful while doing so because they tend to go under your nails and it hurts ) -- I hadn't cleaned mine for ages last time and it had all this fluff and gunk wrapped around the bristles which was impossible to get off, so i got a bowl of warm water, added some shampoo to the water and made it all frothy, put shampoo on the brush then soaked it overnight in the bowl. The next morning I sat down and spent about half an hour gently pulling out all the fluff with a comb and then with my fingers - worked a treat and it looked brand new when I'd finished.

Answer:
I use the square brush but sideways that way it removes lint & dust a lot better I find.I would never use a comb on my MP brush they can tear the bristles.