Vodacom won't cancel a contract after repeated requests

I have been trying to cancel a contract with Vodacom for 4 months now. I have been charge in excess of R3000 after the requested cancellation date.

When I phone the call centre they say that it should have been sorted out but they are not sure why it hasn't and that they will send an email to the technical team to get it resolved asap.

When I complained on Facebook I was told that they forwarded my request to the technical team and someone would get back to me asap. 4 days later and I still haven't heard a single word.