Mtn month-month contracts

I took out a month-month contract of R399 with mtn at the end June 2023 and I had to pay over R400 due to the fact that my debit date would be the 4th of every month......in my mind I know that every 4th of every month I'm gonna be paying R399, to my surprise I see my invoice is R719 due.

I phoned mtn and the first lady I spoke to said to me she couldn't see what the extra money is for and she would transfer me to the right department so that they can tell me exactly what the other amount is for. I got through to another lady who explained to me that the extra money I'm paying would be a 'prorata' amount which I must pay, according to her every customer pays a double amount at their second month of the contract....... I asked her to explain me why am I paying this extra amount she kept telling me that I need to go to the shop where I bought it so that they can explain me, I told her that I am 30km away from the shop that i bought it from-she was very unpleasant to speak to and very unhelpful towards me. Just to clarify that this is not the first time I've spoken to an mtn consultant that is very unhelpful as if they aren't getting paid for their jobs they do.

I asked to be transferred to a manager in order for me to understand the extra amount, someone answered the call and dropped it.

In short I would like everyone to know that mtn is out to **** people, because clearly they bill u extra but can't explain why they bill you. Also another another thing is that I'm not getting anything extra from mtn, so why do I need to be paying extra on my account. I hope this message reaches the mtn representative so that I can get a call back and know why I'm paying extra.