Unacceptable Payment Rejection Fee !

Telkom is charging my Cellular Account a ridiculous & totally unacceptable "Payment Rejection Fee" R 202.70 for a Debit Order that was returned unpaid on 05/08/2021 due to my misunderstanding of the statement amount due since my contract had reached expiry date . I have never agreed to any such "Fee" and it is not even mentioned in the Subscriber Terms & Conditions of our Contract .