Nancy correct my last payment of the contract which I phoned the 29th I shouldn't be paying for August 2022 I have canceled on the 29th june

Time 12:31 I was on the phone with MTN Spoke to Sipho I had to hold again. Nancy answered asking to confirm my ID home address, email address my name and surname Reference of the call for cancelation of the contract that has ended ***

My Question is that Nancy said I would still pay for August which would be my last payment. To me Nancy is incorrectly billing me for August because the same day of the 29th of June was the beginning of my cancelation for the contract which means July is my last Month of payment. What I don't understand is what I am being charged for. I also said that I don't want to use the number anymore it can be given to someone else.