remove stuck seat posts

[cajun bill]

Screwed up and left my seat posts in too long and now they have rusted in place. I have removed the whole seat mount from the deck, but still can't get the post out even tho I have soaked it in Liquid Wrench for several days. I can get the post to turn "by the hardest" with a monkey wrench, but it won't budge to come out of the mount. Even tried driving it out, but that was useless. Any tips would be appreciated.