When i first tried to take mine off, i thought they'd never
budge...
First, make sure you have the correct 12-point wrench,
raise the car and spin the shaft until the particular bolt
you want to remove is at the bottom, then lower the car
so the wheels touch the ground and the shaft won't spin.
Crawl under and give the wrench a quick wack with a heavy
hammer.
Hopefully they will catch and break loose, this worked
for me.