Capital billing service Readers subscription services Fake collections bill for services never received and no one answers the phone yet they are threatening to report it to my credit Los Angeles California

 Received a bill claiming 999.00 dollars in collections for 'readers subscription service' that I never received. I never signed up nor do I receive any magazine or book subscriptions. Up until this collections letter I never received a bill of any kind what so ever yet they are threatening to report the debt to my credit report. I called the number numerous times but no one ever answers and I just keep leaving voicemails. This is completely absurd and don't know how to solve the issue.