Cancellation of contract

I really disappointed with mtn with their consistently poor network, it was only stable for the 1st 4 months then after that it was a different story since from last year November, i just want to cancel the this contract because everytime i complain about their service they always tell me about upgrading to better plan instead of fix the network issue, now they did not deduct hence i had enough money in my account since the 28th of November 2025