Bad service from Mtn service provider

Good day

I'm writing this to get assistance regarding Mtn contract, I did an upgrade for a pocket wifi to an iPhone 14 on 2023 /12/12 and I did not use the sim card package but I was using the phone with another sim and late last year I went to them do a sim swap and everything was going well paying the agreed amount of R1545, 75 per month and this year on April I started paying R2500 and I called them asking them why is my billing so high and one of the customer care personnel gave me an attitude telling me that I have to pay and she never give me a reason why I'm paying more and I payed it, on may the very same thing happened again and I had to pay R2600, again I called them requesting and explanation but I did not get a clear explanation and now I got an sms saying that my bill for June is R2274, 19 of which I don't know where its comes from and the last time I did an upgrade with Mtn the agreement was on the 12 I will get my agreed package and when it's depleted its stop and they will give me my package the following month on the 12 until I finish paying them but now its something else I have to pay more and I don't remember asking them to change my package.please help Mtn is eating my money and they don't want to help me, the only thing that they care about is to call me to do an upgrade on my other number

The number that I'm having problem with is ***

Please 🙏 help I don't know what to do now because when I don't pay them they are going to blacklist me and I want to buy a house