Telkom!!! Blacklisting for no reason!!!

TELKOM ARE THE WORST!!! The are blacklisting me for a invoice in October 2019 but I have a cancellation letter with Reference number in May 2018!!!??? I call them daily to get this sorted but they are either offline or they will get a manager to call me back!!! I am waiting for a manager to call for a week now, how long do I have to wait more??? TELKOM IS USELESS IN SERVICE DELIVERY!!! Will never recommend them