MTN terrible service and refusal to cancel a lapsed contract

I had a contract with MTN which ended in September 2023. As per MTN policy I submitted my one month notice to cancel the contract since it came to an end on 17 Sept 2023. I’ve been calling, doing follow ups since September and the contract is still not cancelled. When I call MTN weekly they always tell me that they are escalating the matter.

What is worse is MTN is charging me monthly for a SIM card that doesn’t even work because contract ended in Sept already. Can you please assist me to resolve this problem please my ref number is: 1- ***.