Poor MTN service!!

What do I have to do to confirm when my contract expires? I've contacted MTN over the past 3 months and they confirmed that my last debit order would be in April 2026. However they have now deducted an amount of R715. I was contacted by a sales agent in March 2026 and I advised her that I am not interested and that she should cancel the contract and she confirmed that she has cancelled the contract. Low and behold after 24 months they debited my account more than what I was paying previously. I spoke to Charlene in Retentions and Nagamzo in Billing who were of no assistance. I want my contract cancelled and my debit order for the 25th month to be refunded. If it is not refunded I will be raising this with Wendy Knowler and making a big noise on social media. I did not opt in for a month to month billing. I was told that it would take 20 working days to cancel my contract. That does not make sense at all! Pay back my money you *******!!! Contract cancellation reference ***