SMSes that I owe MTN and have been handed over to attorneys

I have been receiving SMS claiming that my MTN account is overdue and has been handed over. Problem is, I've never had an account/contract with MTN. The SMS says to call MBD INC for inquiries. The number on the SMS keeps you on hold until it finally the voice prompts tell their lines are buys and to leave a message.

I've left numerous messages on this number, no call back, nothing. The SMSes keep coming, the latest one even shows how much I supposedly owe to MTN.

Can someone please assist.