Allowing customers to use products *******y

Telkom has been debiting my account for a number of months. I keep reversing it at a cost to myself each time. They keep processing it with different amounts and references. Even more than once in a month. According to the debit order rules and regulations. This is *******. They don't have authority to debit my account as I have never signed a mandate with them. So why am I being charged every time and nothing is been done to stop them as they have breached the debit order mandate rules. Why have the rules if you not going to enforce them to all but a select few. From FNB's side if a transaction has been reversed twice. (Yes charge for those two) why are we being charged for ******* debits. Mandate clearly states that if a transaction fails twice a new mandate needs to be signed.