With my bb on my Bobcat it would just not move, then the plastic non-drive side cup shattered allowing my thumb to be pinched between spanner and frame.
So I then used an M8 bolt from an old seat post to hold the bb tool in place. Finally I extended my adjustable spanner by using a couple of jubilee clips to attach a long seatpost (that the M8 bolt came from) to increase the leverage. I'm not sure if the thread on the M8 bolt was the same at the thread in the bottom bracket but with a bit of force it seemed to screw in far enough. Basically I bodged it with a bit of logical thinking and advice from other bike forums.
End result is that it came out nicely. I then hacked at the broken plastic cup with various tools not designed for the job and got that away without damaging the threads.
1986 RM Ritchey "Canapurna", 1991 Marin Eldridge Grade, 1990? Vitus Futural CX, 1995 TREK Singletrack 950, 1996 Muddy Fox Monarch Team, 1997 DMR Trailstar, 1993 Pro-Flex 853, 2001 Santa Cruz Chameleon