Cancellation of account

Hello Peter, well I have a data account with MTN and I called them sometime in April to cancel the account and they said I must pay the cancellation fee of R900 and indeed I paid the amount then on the next day i phoned them to inform them about the payment and they said I must pay an extra R400 and I asked why, I was then told that I should’ve called them right after having made the payment so now it has incurred some charges, I then asked to speak with their manager because I couldn’t understand where was that coming from and where is that written in black and white and I was never helped then I decided to stop paying the account.

Now I got an email from them that I am owing them an amount of R2070 and indeed I paid them just now, so now the issue is that my name has been uplifted to credit bureau. I need assistance with cancellation of this contract and for my name to be removed.