That’s the thing he doesn’t want to use heat because it might damage the frame, he’s already soaked it in plenty of rust remover, or something of the sort. He’s already drilled a hole through it so the post is already a write off, and he’s tried using the frame as a lever and it still hasn’t worked.
Instead of expanding the seat tube with heat, contract the seatpost using ice, that should work.
If not brute force will help a bit, but for something like this you have to use strategy, in this case either the rust or corrosion has grown so much it has fused the tube and post together depending on what material there is.
@Trebz are you sure you don’t have any pictures because that would help a lot.
If all comes to a loss you’ll either just have to live with it or have it drilled out. Or just have the seatpost man remove it for £79
Even though if it comes out with cold water youll have that £79 to spend on a new seatpost!
I’ll post some pictures tomorrow gents. Might be after 8PM.