Never Ending Virgin Mobile Harassment

I have been continuously harassed by Virgin Mobile debt collectors for more than 10 years. I have never had a Virgin Mobile account. I have asked them to send me a signed contract or voice recording of a contract to show I have every had a contract with them. To show me one record where I have ever made a phone call using Virgin Mobiles phone or network. I have only ever been an MTN customer. I am sick and tired of Virgin Mobile not sorting this out. Just crazy you can demand money from someone who has NEVER used your services.