If you can get a left-hand bit, (turn the other way to cut) that might heat it up enough to get it to break loose once you have drilled into it a bit. Hardest part is, getting the bit centered on the bolt...... I am sure your FIL will have some suggestions for that as well.

 

On he has suggestions for everything, I can never get him off the phone lol. I already have left handed bits and a center punch 😀
I shall try that first. I'm not a big fan of them. Now the turbo sockets those things are awesome!!!

 

Yeah, they work great if there is anything left for them to get a hold of.