After stripping the splines from a Shimano BB tool trying to remove a BB, I took it to the LBS and they got it out easily. They have special powers, and probably a half-crazed gorilla kept in a cage out the back.
I'd find someone with an impact wrench. Either air or electric. I've used mine to remove several seemingly stuck BB's...it's never failed yet. Adding a "cheater bar" to increase the leverage on the socket is likely IMO to end up damaging something. Try a local garage or tyre depot.