I'm sure you also beat it a few times to try and break it loose... You've no doubt sweared at it enough. Best we can probably tell you is keep at it. It'll happen, but keep at it.
I nearly gave up on an exhaust stud from the front to back manifolds, tried it all...day or so on one manifold stud that broke. My mechanic buddy told me to hit it with the air chisel...to break the nut welded on...kept tryin...couldn't. Then he came over...after my two day ordeal, put the chisel to it for 5 seconds...DONE. Just a matter of 5 more seconds....
Keep at it, it'* gonna hold on for life and you can get it...just be patient
00 Regal GS: All kinds of cool stuff.