Payment Penalty

So what happened these people think when they make a mistake that the client should pay for the mistake. I have a monthly payment arrangement. I paid them head of time the full monthly fee. Not think about it, did not realized that they will still do the debit order. Need less to say I did not have enough funds in that account therefore the debit order returned. They send me a notice saying the debit order returned and I have to pay R350 penalty. But because they did not remove the debit order after receiving the full monthly payment. Now I have to pay. I also want to be in a business that force clients to pay if I made the mistake.