Unhappy with cell c

During december 2019, i called Cell C for a SETTLEMENT. Paid amt i was told - IN FULL. Four months later my savings acc was debited with R 2 715-16 - when i contacted them they told me it was amt for data etc for dec and jan. I first advised them that i settled the account in full in december, then wanted to know why they waited FOUR months to process a debit order? I advised them i dont have full amt once off - the acc's dept can contact me for payment arrangement. Nobody ever did. For four months they continued to process the debit order. Then last month i was "defaulted" on my credit record for R 5 430-00??? DOUBLE???? WHAT IS THE POINT OF REQUESTING SETTLEMENT BALANCES IF THIS HAPPENS?