Telkom Account Harassment

Cancelled ADSL account on tel no -***-in 2018.Account no-***. This is now the 3rd time I am being hounded by Telkom/Collection agency for suspended line and outstanding monies. I have twice submitted proof of cancellation but still am being harassed. Telkom ref no-***a. I am sick of having to prove that their accounting system is a mess. Can you please assist in resolving this matter.