Please cancel my contract with immediate effect

I had a contract with Vodacom expiring last year Nov. I first made a call to cancel in October and I was told to phone in November which I did. I thought my contract was cancelled as I did not need it anymore. In December I was debited and I called them on the 22nd to find out why, th consultant told me that my contract was not cancelled. I asked her to cancel it for me. I received a call from Vodacom beginning of this year offering me another deal and I told them that I don't want it and the consultant told me that my contract was not cancelled. I phoned again and cancelled it. Two weeks back I app**** for a bond and I was declined due to my Vodacom being in arrears. Then I phoned Vodacom last week and spoke to a consultant who was helpful and told me that her manager was going to listen to the recordings and get back to me by last week Friday. Today it is Thursday and I have not received a call from Vodacom. Monday I received a call from the collections dept in Vodacom telling me that I have been handed over I needed to pay an amount of about R2000 I told her that I cannot pay for something I did not use. They must check their records and explained the journey with cancelling my contract she said she will escalate the matter. Please assist as I want this property and I cannot lose it because of something that should have been cancelled last year.