Additional amount charged, not normal discount rate

Vodacom charged me an additional amount on my contract, i contacted them and was told the amount would be corrected, but it was still debited on 1 Dec 2020, still waiting for this amount to be refunded to me. I did call the helpdesk, and they told me it might have been a pro rata amount, before i cancelled my contract i called the helpdesk in nov, and was told as well as was sent an sms stating the discounted price was still loaded for nov 2020. And was also told my installment price would be the same if i kept the contract, stated in vodacoms terms and conditons aswell. Now am told if the ctedit office declines ot i won't get a refund, but i explained all this to a consultant in nov already. Please go through your call records and assist with a refund or atleast a credit.