That happened to me once. I was trying to rebuild a brake caliper on a 65 Corvette I was restoring, and the bleeder valve bolt was stuck. I used an easy out, and it broke flush with the surface. I called a few local places, and they said that with a broken easy out in it there was nothing they could do. I called up a company that sold rebuilt calipers for that car (Stainless Steel Brake Corp), and they said, "throw it away. You'll never get it out by yourself." He said they could get it out, but they specialized in it. I wound up just buying 4 rebuilt calipers from them. They gave me a full core charge on the damaged one. That being said, it was the only time I broke off an easy out. But I agree it can turn out badly!