Telkom and Debt-In

I cancelled by phone and adsl line August 2018. Suddenly 14 months later, I am now harrassed by DEBTIN for monies not paid. At the time of cancelling my phone I was in credit with Telkom. Emails to telkom get send back. I am now being invoiced with a different account number and harassed by DEBTIN. I am waiting for their email to send my proof of cancellation.