I had this happen when I installed my alk. The bolts corrode at the very tips where they sit proud of the subframe and won't come out unless you wire brush the tips of them. It's probably a galvanic reaction with the subframe being Al/si.
If you can get it threaded back in, clean up the exposed portion at the top before you try and back it out again. If it's seized solid, don't bother trying to drill it out unless you've got a seriously heavy duty drill. I tried with my pistol drill and just rinsed through bits. It really needed a pillar drill on it at that point but honestly it's much quicker to replace the console portion of the subframe - mine cost £20 from a breakers on eBay plus the bolts that mount it to the body.
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