MTN Phone Contract

Oct 2021 I took a phone at MTN using contract. September 2023 the contract was due to end. I have been calling MTN from June to September 2023 to cancel my contract. Instead I receive an email with a statement for October and worst of all the amount I am supposed to pay has went up.

@MTN what could be the cause of this as I have spoken with several agents and they assured me that the cancelation of the contract has been submitted.