Those pedals NEVER come off easily. Heat will definitely help, but beating - at least on the shaft, will cause more problems. Most likely beating is part of your problem, since it tends to upset the shaft and make it even larger.
Since you have it loose enough to rotate on the shaft your next step should be to file the shaft outboard of the pedal to reduce its' diameter slightly.
Just think how much better you will feel after you've won this one!