Gring the heads off, that is what my mechanic done. Grind the heads off and once you can get it off use a good quality stud extractor to remove the remnants of the bolt. However the state of his overalls was not good, there were hot rock burns everywhere and he was not in a good mood when i picked the car up! and he had a ramp, so good luck getting a grinder and your head in the wheel arch!!!!