Cell C Distpute

I had a cell phone contract with Cell C about 4-5 years ago and I called in to enquire about cancelling my contract and being converted to prepaid. the agent then advised me of how much I should pay for my request to be executed and I made the payment as instructed. to my surprise, I was recently told that I have an adverse listing loaded by Cell C on my credit profile, which is ABSURD as I made payment according to what I was advised by them and had the impression that the account was paid off all along. No one even contacted me to tell me about extra/cancellation charges back then, and I wasn't even notified before I was listed. which is against the law! I demand that this listing be removed from my profile as you didn't comply with the requirements in the NCA.