I had a stuck post, and the best advice I have is until it actually comes out, it seems it is going to be stuck forever - don't give up.
Mine eventually came free after days of not moving. I used tons of oil and bolted a old seatpost in the seat guts and after a lot of bashing got it to move a mm to the side (rotate). Then after more oil and bashing I got it to rotate a mm in the other direction.
It then took about another couple of hours or so of more oil, more bashing and only managing a degree or so extra rotation every now and then - still convinced it would never come out.
I guess that no matter how hard your forcing it, it needs a long time for the oil to seep down into the new gaps you create from the extra degree of rotation.