Make sure you follow the FDCPA when disputing the false claim. You can learn more at consumerfinance.gov. While you are on the website, report Keystone Collections. The Feds love to keep track and fine collection agencies for their false debts. If you find that Keystone broke FDCPA laws, find a consumer protection attorney to potentially sue Keystone. The attorneys usually are free for string cases and you can claim up to $1000.