One other way is to remove the crank bolts and go for a ride. That should loosen the cranks spontaneously. Stay close to home because when one comes off the bike will be rather hard to ride the rest of the way. This technique will ruin the crank arms but you don't intend to reuse them anyway, right?

However, if you go to a bike shop and have them pull the crank arms properly you might be able to sell the crank for enough to justify the trip.