Vodacom cancellations misleading

I recently called in May to cancel my contract. But the cancellation department then told me that for being a good customer they would like to offer me a huawei mate 40 pro on a discounted price. I obliged to hear how much my upgraded contract and existing contracts would amount to of which the lady after asking 3 times said 760 rands. After that I waited for the quote which I never got and the phone arrived as the deal was too good to let go. After the month end I see i need to pay 1200rands of which then means I was misled falsely into agreeing for an upgrade. Now afyer mondo investigated and found wrong doing on the part of the operator. Vodacom cancellations call and try tell me what I'm paying for but then don't want to acknowledge wrong doing. If this is not sorted by tomorrow I'm taking legal action as there is proof of recording with me asking 3times what my new installment will be