FE's broken bolt removal tips:

A hammer drill with left hand bits is very nice
spiral flute extractors work best
drill as large a hole as you can without eating threads
Start with a very small drill bit and work up in size, or you'll fry bits
in any case, lube the drill bits
whammo the snot out of the bolt stub before inserting the easy out, and hit it several times
with the ez out inserted, using a knuckle buster adj wrench, put the ez out under heavy torque, short of stripping/snapping it (it's case hardened steel, and WILL snap under too much torque) and while holding the torque, apply sharp blows to the front end of the ez out.

The purpose of the above procedure is to shock loose any corrosion/crud holding the stub in place, and the shocks will help overcome simple friction.

Also, an overnight soaking with a 50-50 mix of acetone and dexron aft will help a lot, plus another spray just before you start with the ez out.

I bet the belleville washer got lost in the process? In any case, order a new one. The convex shape cushions the bolt. Of course, order the last version bolt, with the short hex.

And may St Hubert of Liege, aka St. Untwistus, guide you along your way, and that you do not need St. Barbara...