Actually when you have a hole drilled in metal; heating the metal expands the hole Aluminum or Steel.
Heat (and something like PB Blaster) is extremely helpful in removing broken off bolts when using an Ezee-Out.

He could have the Auto Club Tow his car to a shop and have them EDM (electrically burned out), The burn it out while coolant rungs through the Electrode and keeps heat the heat under control.

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84 300D, 82 Volvo 244Gl Diesel