Something's wrong if it's that stuck. Lefty loosy, righty tight, magnet doesn't work. Hmm. Is it already loose but you just can't get it out? In that case, I'd make a slip knot noose and pull it out if you can't find a magnet strong enough. If you're still turning it and it's not coming out, then it may be stripped. Are you 100% sure the socket is making full contact? Try fitting the socket on one of the new spark plugs to make sure that it's the right depth. After that, I'm all out of ideas.
2009 335i Coupe 6MT Blk Sapphire / Blk Leather
2007 328i Coupe 6MT Blk Sapphire / Blk Leather *Sold
1985 Toyota Corolla GTS 5MT 1.5-way Slvr / Blk *Sold
1987 Toyota Corolla GTS 5MT KAAZ 2-way Blk / Blk *Sold