Cancelation not actioned

I have 2 emails from Vodacom confirming that my contract will be terminated effective end July, when it ends . This was in April. Knowing their level of incompetence, I decide to send them a reminder email to confirm that i do not want the contract extended. Muneed Kolia, responds via email, that i will be billed again in August. Why since both myself and vodacom have agreed to end the contract. If the was usage , then why was it loaded? I am not going to pay for something I did not ask for. Vodacom has been reaping me off, every opportunity they get. I want nothing to do with vodacom and my contract cancelled, effective 25th of July as per our agreement and emails confirming this.