MTN did me dirty

After a good 9 years of being a loyal customer to MTN they did me dirty,

I had a 24 months contract of a phone, Minutes and data with MTN which ended January 2025, but in February they continue billing me when I asked why, they said it's like that, I told them I'll make a plan to pay, made an arrangement, only for MTN to block everything and the data, what is worse is they blocked the data usage and minutes but kept on billing me of something I am not using, now when I went to MTN this past week they said I am owing them 3 x the money, when I check the invoice statement it says they have been billing me for the past 3 months on something that they blocked, on the phone I was only left with 1 month to pay it off, but they charged me extra 2 months, please help because when I go to the store they said my acc has been handed to collection, when I called collection they keep coming up with stories and transfer me to someone else until they hang up without resolving my situation, I am willing to pay off my contract but not the extra billing of something I didnt use in the likes of data and minutes because it was MTN's decision to block them not mine. Please help🙏