You raise very good question. A 1099c is a form that companies send to the IRS when a debt is canceled. Some of the attorneys I have spoken with have indicated that if a company sends a 1099c then the debt should be considered canceled and no further collection activity should take place.
I would recommend you go ahead and contact an attorney to get their opinion. You should be able to get an initial consultation for free or at a low cost. If it turns out the debt should be considered canceled, then you can send the debt collector a cease and desist letter telling them not to contact you and explaining why. They would then only have the option of taking you to court, which they may not want to pursue if there is not good chance of collecting.
You may want to contact the coauthor of the California edition of our ebook, at BrennanLaw.com. Do let us know what he has to say. (Because this will be a legal consultation, he needs you to contact him directly rather than through this website, which is for educational purposes.)