Spark plug wont turn rusted in

This could turn into a very serious problem if not handled correctly. I suggest you let a highly skilled professional take over this problem because if you damage it too severely, you're going to need a new head but an experienced tech should be able to install a heli-coil repair, even if he ends up having to drill out the plug if it breaks off. Continue to soak it with penetrating oil in the meantime but don't get overly aggressive with trying to get it out.