Day light ******* .... I want a refund

Hi there I have a contract with Vodacom and I was a bit confused about the debit date if it was the last or first day of the month. So I transferred my debit order amount into my account on the first of the month. he very next morning I saw that the debit wasn't deducted from my bank account and I immediately went into the Vodacom self help app and saw that I owed Vodacom R125.01 and did a immediate payment for that amount on the app using my bank card. I then since checked the app and the amount still showed owed on the app I called the contact centre two days after making the payment the consultant confirmed that the payment was received and said that Vodacom will charge me an extra R100 and odd cents for the unpaid debit order...i feel that this is unfair because I paid on the realtime app. What can I do about that? I now checked my statement and there is an extra charge of R100 this is **************** for pensioners I'm using my daughter's Hello Peter account. Sharon Peteers