MTN contracts

I entered into a 24 months contract with MTN, for 20Gigs of day time data per month. The contract expired end of February 2022 and they extended my contract without my consent and keep on billing, at an even increased amount. I called in March when i received their email about an account in arrears, they advised they couldnt cancel due to an outstanding amount. I asked how is this possible when my contract expired, none of the consultants could tell me why they billed me when the contract ended. I paid amount for the sake of peace, they have billed me again for April. I emailed, probably the 5th time now or so, they still tell me i have to pay the new bill before they can cancel. This definitely not fair, why do we enter into contracts when they have to decide on my behalf that the contract has to be extended? I dont even use the line/service anymore, atleast get a person's consent before inconviniencing them!!