The previous owner of my car neglected to tell me that one of the water pump bolts was broken off inside the housing. I noticed it when I had a nice puddle of coolant under my car last week. I got the water pump off and tried to remove the broken bolt with an easy out. I managed to break the easy out and now it is stuck inside the hole I drilled in the broken bolt. I now have to drill through the easy out. I have tried new cobalt and titanium tipped drill bits and they don't work at all. What else can I use to drill through the easy out?