Vodacom refuse to close account at all costs

Vodacom and their debt collection Burnard and Associates are now harrasing me over an account that was closed in 2020. So vodacom will not rest to give me a headache even after so many years of leaving them. If I knew that having a phone contract from vodacom was like this.. Now I'm recieving calls, smses, whatsapp message about account being in arrears, an account that was closed. Vodacom neh. I have no more words for them. The Burnard and Associates are now sending me endless statement tha I have no idea how they came about. Sometimes vodacom will list my account as missing payment and sometimes they will not list it. I have no idea why they would say they closed the account but keep it active even after they said they will close it. Or maybe that is how they rob people....