The worst network

My account was *****ulently upgraded and I reported it. Vodacom froze my account during investigation and later reimbursed me the money that was taken from my account. I then asked them to cancel my contract as it had expired anyway of which it was done. 3 months later Vodacom registered me on credit bureau for unpaid payments for the time after the account was closed, I called them to rectify it and they told me that they will send me the confirmation letter after 48 hours and nothing came through. I called again and was moved from pillar to post with no definite answer.