MTN *****ing My Money

I have had my contract since end September 2025. First debit order (by mandate) was deducted on 31 October. On 1 December the October and November payment was deducted - when October was already taken!!! This week I received a statement telling me that a deduction will be taken for October, November and December. You are *****ing!!! I contacted customer care, they said they want proof of payment. How the hell do I get a proof of payment for a debit order mandate?! I also sent my bank statements where these payments have gone out of my account. How can your debtors department not pick up payments that were taken via mandate?! This is ridiculous.