Stuck seatpost (I've tried everything)

OK folks, I bought the best part of a bike (off organicorigin) and school boyed it and didnt ask/check if anything was stuck in, guess what? EVERYTHING is stuck in... couple of days, WD40 and a large hammer got the BB out so I am now on to the seatpost, alloy (i think) in cro mo, tried WD40 and previously mentioned large hammer with no luck so moving on to chemical based methods.. going to try coke first, then ammonia, and finally caustic soda, am I right in thinking caustic soda will render anything alloy unusable? cheers.

have a read through this: http://www.velonews.com/article/99640

i might use caustic soda as a last resort. if you're not precious about the seatpost, then i'd use a benchvise first, then a hacksaw if that doesn't work, and then move from there.

good luck.