Spartovi, i'd recommend
first, never underestimate the power of wd-40 or liquid wrench(leave them on all night to avoid tendinitis) if you've tried the vice grip method, and that's failed too, then
you have another (maybe last) resort. I use this on the car all the time. First you need a set of titanium drill bits, which drill through the softer bolt metal. They look golden in color; you can get them at an auto parts dealer; buy a whole set. Next, you need some bits that are called "reversible" or some such (the parts dealer will know you need them).
Drill with titanium slightly smaller diameter than the bolt; remove the bit and then drill in the reversing bit (you must have a drill that can drill in reverse for this). If you're lucky and have a powerful drill, the drill torque will loosen the bolt. Otherwise (which is usually the case) remove the drill and tap the bit gently from side to side with a hammer. This usually loosens the most stubborn rust/corrosion so you can twist it out with an adjustable wrench. If not, spray yourself, the machine and everybody else again with wd- 40 or liquid wrench and try again in the morning. Lastly, if the dang thing still won't come out, you can drill with the same size titanium bit as the bolt itself and use a slightly larger bolt/nut than you had before.