Bad service. Contract cancellation failed after giving notice on time. They're continuing to bill me

Its frustrating that i called in to cancel my contract on time (June 2020) but I am still being billed for the same contract. I spoke to Nadine Davids after speaking to 5 other people (1 of them (KG) confirmed on the 6th of June at 14:58 that my contact is cancelled), but Nadine says Vodacom's policy doesnt allow her to help me while i have arrears even after i mentioned that those arrears are caused by the contract that should have been cancelled. Josline Palè said she will ensure that my contract is cancelled and i wont be liable to pay for it in the 10th of August at 12:28.