Unhappy and Extremely angry

I cancelled my month to month contract at the on the 23 September 2024 and returned the router together with the sim card back to the store, they made the cancellation and gave me the IRMS number: ***. To my surprise, they kept on deducting for 2 months even though I do not have the sim card anymore. After they deducted in October, I went back to the store, where they assisted in calling the 135 customer service number and it was confirmed that the contract has been cancelled, they also said they will credit my other contract as they cannot make a refund, it never happened, they deducted again in Nov for the same cancelled sim card. I called them and they informed me that the contract is still active, but they took the sim card in September already. I've run out of options, I do not know what to do now, I'm very frustrated. I've been going up and down to mtn which is over 75kms away from where I stay and it is costly. I am tired and just need for this whole issue to be resolved. I cannot be paying for something that I am not using. I even suspect that the person that took my sim at the store is probably using it but I'm the one paying for it and it that case it would be *****. Can mtn just resolve this matter because I am tired.