Or contact the Taxpayer Advocate.
https://www.irs.gov/taxpayer-advocate
It doesn't make sense for a start that you would owe $3000 in tax if your 1099-C income was just $3000. Was there something else they adjusted? If you can't make headway with the IRS you likely need a local professional to look over all your files and correspondence to figure out where you are at this point.
