Frustrated

I am at a wits end with MTN. I have contacted the complaints department on 3 occassions. To date I have not received a response. In August 2021 I received a call from the Telesales marketer stating that they are upgrading the customer contract for an additional R 60.00 for month. At month end instead of R 399.00 deducted an amount of R 706.33 was deducted. I contacted the customer care department - I was informed that this is a once off deducted. I have now received a statement for R 539.00. I have requested the recorded the voice recording of the conversation 6 times already. Can someone please advise who authorised the deduction over and above the R 60.00. thank you