MTN and their Overcharging

I was contacted by my service provider to upgrade my account. I took a sim only deal where they offered me a 200mins and 30gig of data deal at R308 per month. It ended up being 200mins and only 20gig of data per month, but they did a reoccurring 25mins times 8 making it 200mins. I then received my new account this month due for the 1st of November 2022 and it has increase. They are now charging me for 16 times 25mins and I only received the 200mins and not 400mins. I find this unacceptable and would like my contract to go back to normal the way it was before my upgrade as I do not think they know what they are doing and find it unfair that I must pay for all their mistakes.