vodacom harrassment

I am being harassed by Vodacom and its debt collectors. my account with Vodacom was closed and settled with help of national consumer council, but every 6 months vodacom debt collector call me and threaten to blacklist me. I have email evidence that the account is closed. now recently they have blacklisted me again for the same account through VVM debt collectors ref:I ********** . I really need help on this matter.