Very angry and dissappointed

I am very unhappy with Telkom. They debited me on the wrong date which was a day before my pay day and now they say they will charge me R202 for unpaid- is that even legal. Then they said they can not re-run the debit order and i must make a manual payment i did and again i was debited the amount. So Telkom is telling me that for an error that they caused i must be charged double my monthly account fee, is that fee even allowed by the NCA to charge a client over 50% for an unpaid on their account