Mtn committing *****

My contract with mtn was expiring on 01 November 2015. I went to mtn at 14th avenue in Constantia kloof Johannesburg, for advice on how to terminate the contract. I was advised to give a notice on 30 days in advance so as I did. To my dismay is that mtn billed me for November month. I tried to call them and told that I was supposed to call them again after calling them for a notice. I was told that i must keep on calling them to terminate the contract. They don't want to terminate the contract because they know that in our country business have the right to commit ***** on customers.