Contract cancellation

I've been trying to cancel my phone contract for the last 2 weeks now. I've spoken to numerous vodacom consultants and they all tell me the same thing. They advised that I am on an old system and they do not have any contact details for them. What blows my mind is that they can very easily send messages and call me with the same promotional deals that are on the supposed new system yet cannot assist me in cancelling my contract. I am dying to get out of it ASAP.

Please help!