Update clients profiles. Being harassed for Acc paid off almost 2 years ago nxa

My cell c number was settled, converted from contract to prepaid yet I'm still being harassed. I have tried calling Cell C, been holding for contracts, then collections for hrs, sent emails, but nothing. I have told everyone I know to cancel their service with this nightmare service provider. Good God, lawyer's are harassing me for an account that was paid off. Next best thing my credit profile is affected by their *********** staff. Phone call and this SMS nonstop. How many times can I keep telling these ppl the account is CLOSED my line is prepaid. Plz fix this toilet service. Don't ignore! May payment overdue on ur Cell C acc ***. Pay now! Use Bank ***, branch 250655 or call SSDA on ***. Bal R703,00