Commenity issues credit cards for many different stores. If you do not have one of these credit cards or are not behind in payments, you need to send them a certified, return receipt letter telling them to cease and desist calling, make complaints to the proper agencies, and then sue them if they continue to harass you.
Read up on your rights here, get template letters to send and also make a complaint at this government site: http://www.consumerfinance.gov/
Also file a complaint with your State Attorney General's office.
List of State AG’s offices: http://consumerfraudreporting.org/stateattorneygenerallist.php