Termination of contract

I have contacted MTN customer service on 6/2/21 to cancel one of my cellphone contract +*** because it was ending on 16/3/21. The agent stated that the contract will be terminated automatically and i can port the number as it will be a pay as you go number. I then received a call from an upgrade agent on 18/3/2021 asking me to update that number and suggesting promos that he has. I once again asked that this number should be canceled and requested him to ensure it was canceled. I called MTN customer on 27/3/2021 to request cancelation for the third time and was told to call on Monday. Today, 29/3/2021, I called and was holding on for 30min, no answer so I called again, an agent answered my call and was busy checking why this contract was not canceled, then cut the call. MTN has always given unsatisfactory service, with in-compliant agents. I will not be paying for this contract and surely be seeking legal action against ********** transactions done by MTN