poor service and actual defradinging of customers by MTN

I had adata contract with MTN, no device just. Simcard, I called l, to terminate to contract , I was told pay ,aR567.83 as apenalty fee, I paid R600 , to my shock months later account is handedover to company called MBD I made arrangement anyway to settle account for an amount of R640 for the account to settled, that was in January 2022, when I made this payment . Since the everysecondvday I get acal or email from MBD that I still owe same amount of Money dispute me sending them proof countless times , and calling them. Eventually I reached out to MTN , now they want me to pay for the interest they added from January upuntill now because they just recieved my payment never bordered to settle and close the account . Instead they keep on add more money to it each month, in the meantime this is impacting my credit profile , and they do not want to do anything about it.

wherein I never even should have paid this amount because it's not my fault they they tdid not close my account when I initially requested to close it t. and paid the panelty,