Greasy Hair

I was wondering if anyone can give me any tips on how to stop my hair from getting so greasy??

I grew my perm out a few years ago as I want to go straight and I noticed that it went greasy the very next day after washing it, I tried different shampoos and conditioners, even tried not conditioning, but nope it just went greasy the next day.

I was told about the Aussie range, that didnt help unfortunately, so I ended up going curly again as that seems to be the only way my hair stays dry looking and I dont need to wash it every day,

My fringe is straight and I find I have to wash that every day and give it a quick blow dry just so it looks as good as my curly hair.

I even tried not washing my hair for over a week, obviously not venturing out the door as I looked awful when it was straight and very greasy as I heard the longer you leave it that it puts all the oils and nutrients back into your hair, but nope it just didnt work.

Please can anyone tell me anything I could try to stop this happening, I would love to hear some hints and tips from anyone. Thank you xx