Ending a contract

I am so disappointed with the service I got from MTN and that gives a person lots of questions when they feel like taking a contract with them. Its's so easy to get it and and so difficult to end one with them. I took a contract with them and it was suppose to end by the end of February but they still keep on deducting money from my account and I don't know for what. They took their agreed amount the again the following month, last month R 155 was deducted from my account not knowing for what and I had to reverse it from my bank account. This month again R 321.40 from my account for what I don't know. I have called the customer serve to cancel and I was given a reference number and I was informed it will be cancelled after five days. And I also emailed their customer care, some lady told me if I don't use my phone it will be automatically cancelled on their side but not. I don't know for how long will I have to keep paying MTN for a contract that has ended and in future I don't think I would love to take any contract with them anymore after this bad service I got from them.