Heli-coil broke off in my oil pan. Oil plug won't fit anymore. Help!?

I recently bought a 2003 Chevy S10 4.3 V6. I decided to change the oil in my driveway and when I pulled out the plug, a piece which I've been told is a heli-coil came out with it. It looks as though the heli-coil broke. Shop says new oil pan would be $900 labor. I bought an oversized plug but it's still to small to just thread in there. They said there is no double oversized plugs. Do I have any good options other than $900. Can I put a second heli-coil in? Is there a plug or bolt I can buy somewhere that is the same thread size? The plug that fits into the heli-coil is M12-1.75. Any help is appreciated.