Vodacom ********* behavior in cancellations

I have been speaking to the cancellations department & collections department both telephonically and via email since last year to cancel my contract which has met its expiry date but this has not happened and now i am being threatened by Vodacom to be blacklisted. I think Vodacom is the worst service provider and is run by a bunch of ****** who clearly prey on innocent people and ****** them for services no longer needed