VVM debt collections

VVM debt collectors has been harassing me to pay them an amount R787.09 since around 25 May 2021 for a Vodacom account they say was handed over to them. I had explained to them that I don't owe and never owed Vodacom that amount my contract with vodacom ended in August 16 2020 and had done what was required of me and phoned a month prior to cancel the contract which was what I was told to do should I no longer be interested in carrying on with the contract. I sent them a email with attachments of letters I wrote to Vodacom regarding the matter on the 17 August 2021after speaking to a lady by the name of Nompumelelo who suggested I send an email and she would escalate the emails to vodacom. I received a ticket #79442 for the e-mail. Prior to this VVM would send me messages with a whatsApp link as well as a number to call. I sent a WhatsApp on the 27 May 2021 with attachments of the dispute emails I wrote to Vodacom. I never received any response. I again send an email yesterday the 08 September 2021 enquiring about the ticket number and how far was the matter. No response. I phoned the *** number to request a call backat 11:49 on 8 September 2021 no response. I later phoned to speak to a consultant all were busy for at least 10 minutes. I tried the live whatsApp chat. No response to that. Friday a guy from VVM called and offered me a 10% discount on the account if I made a payment during the specified time of the offer. I refused to pay and told him my story and that I am still waiting for a response from them regarding an email I sent disputing the amount. He told me if I don't pay I would be black listed. I am so tired of this disputed which started with vodacom after the end of my contract in August 2020. I just want them to sort this account out with Vodacom and get back to me. Ref I***. # WIN