I am suposing that what was done at this site would work on yours too. However your Glow Plugs are shorter than the ones in this article.
http://alan.mcreynolds.googlepages.com/howtoremovebrokenglowplugs-mercedesom606
If you take it to an Indy and he cannot get it out he as the choice of Drilling It Out Himself And Possibly Messing Up Your Head. He would have to take responsibility for that.
Or He could play it safe and at the same time make more money by removing the whole Cylinder Head and sending it to a Machine Shop for them to Drill it Out.
If you were in business which would you do?
You could also pull out the Injector on that Cylinder and spray some PB Blaster on the Electrode end protruding into the combustion Chamber to soften the Carbon.
You also might be able to see if the tip of the Glow Plug is swollen.
If there is something sticking out maybe you could slide a nut over the end and Weld it to the Glow Plug. That would also supply some serious heat.
I would not worry about heat and PB Blaster. Some Heat helps wick it in between the parts.