Seatpost removal attempt

I'm running a hacksaw blade into the cut-off seatpost of the Trek that I bought yesterday. I've tried everything else suggested by Sheldon Brown (passed away, but never forgotten). This is the second slit I've cut inside the seatpost along the entire remaining length in the frame. I'm afraid of cutting the frame, so I may not have quite gotten through far enough. I do not want to concede defeat here. I want to be able to handle such situations and emerge victorious. I'm not there yet.