MTN give false information

I had a Black Friday upgrade where the 2 years was up and I called in on the Black Friday in 2020 again to see what upgrade offers they had. The only offer was a sim for data only and could not be used in a phone. I advised I couldn't use that and the consultant said I can keep my current 3 contracts which had the special on for the same price and I could upgrade later if I wanted and I would be charged the same. I left it at that and a month later in December MTN called me with an upgrade offer which I took for my 1 phone contract and I asked again that do I need to upgrade my other 2 contracts and the consultant also advised that I don't need to upgrade them and they can keep going as before with the same package at the same price. Then in February I looked at my bank statement to see that MTN charged me extraordinary rates for the 2 contracts I didn't upgrade for the 2 months. For January they charged me R4032 for all 3 phones I didn't upgrade and in February they charged me R2648.13 for the 2 contracts I didn't upgrade. I called and explained what had happened and that they could listen to my calls and again when I upgraded where I was assured I would not be charged more. I called so many times and was promised a manager would call me back, they never did. I called them monthly as it was taking too much of my time. I called and spoke with Leshana in April who said there was a credit that would be added to my account, but this never happened and I called and called and have numerous reference numbers, but still my query is not resolved.