I have gone through the same type of frustration. I will generally not resort to a using a maul (mol) but did pull out a ball pin hammer to help insert the wrong size hexagonal cup screw pin crappy thing without much luck. Drill, correct bit, retap the hole, bought some new bolts from Lowes that will take a regular wrench or socket (No phillips head or flat head to get buggered up and ugly). No new problems,
Hex bolts and hex wrenches can be a big pain in the rear. Drilling the old bolt out can be one of the worst ways to correct the situation especially if the surrounded by a softer metal. try the liquid wrench stuff first, maybe a little heat (not good for paint). The sugestion of tapping on it is good for any stuck bolt.