Unfair to customers

Months after closing my line with Telkom i got a mail from Nudebt Management saying I owe them money. The calls and emails have not stop after i over explain myself so many times. This is at a point where it’s given me anxiety and stress. Telkom does not want to take accountability of Incompetence. From them your credit record will without further notification be updated on various Credit Bureaus to reflect the above Adverse account. This bullying