Unsatisfied customer

Vodacom has now charged me the R100.88 of penalty fee which I don't understand because I paid their money on the date that I said I would pay with now am surprised why they charged me that penalty fee..debit order didn't go through because I only had the money that I know that they should deduct now they tried to take more of that amount, that is why it didn't go through, I did called on that day and their consultant told me to pay with my capitec app which I did then am surprised that they have to charge me that amount as I did not skipped the day or payment..I really don't understand how Vodacom works..