MTN KEEPS TAKING MY MONEY EVEN AFTER CANCELING MY CONTRACT!!!!

I've been calling MTN to cancel my contract for the past 6 months now, everytime I call they give me a run around!!! From one agent to the next....!!! I went to the MTN store, they said they can't help me..I need to call 135? Why?? I did my contract their at there store!! Why can't they help me cancel it?

They did this for 6 months! I went back to the store and demanded that they call 135, and when they did, they "canceled " the contract and said they'll send me a confirmation email in 24 hours. I've been waiting for this and I HAVEN'T received this email. It's been a month now, and they sent me an invoice???? Why ?? I called again to demand for that they send me a confirmation email, but no one is helping me. They keep saying "it's canceled" . So why did I receive an invoice? Why is it hard to send me a CONFIRMATION EMAIL????