Vodacom Incorrect Billing issues

Vodacom has done it again. This time with an incorrect billing. They tried to debit my account for an amount of R1200, and my monthly premium is approx. R498. When I called the call center to query this (time of call was 08:05:39, November 3rd, call duration was 19mins 37seconds), the consultant was unable to accurately explain how this amount was outstanding. First, she says it was for a data bundle that I had bought, which was already paid for. She then agreed with me. Thereafter she explains to me that it is because I am billed in arrears and the R1200 is for my SEPTEMBER premium. I work with billing, I know how paying in arrears works, this is not the case. She then proceeds to tell me that it is because I was charged a "pro-rata" amount for May (I took this phone contract out in May) so they only charged the full contract amount for May at the end of June, and June at the end of July etc. I have been with vodacom for a very long time, so has my family and this has never been the case. Added to this, when I asked if I would like the team leader to explain, and I had said yes, I was then told the Team Leader would have to call me back to explain this to me. I asked them to contact me at Midday today (12pm November 3rd 2021). I have yet to be contacted to resolve this matter. This is seriously disappointing service from Vodacom. I really hope to have this matter solved urgently.