cancellation not fulfilled

requested twice that my contract must be cancelled and yet i am being billed for months for it. I called numerous amounts into Vodacom requesting my line be cancelled, on two occasions the agent confirmed this was done, last month and this month im still being billed for it. When i requested it to be cancelled they tried convincing me to keep the line but i dont want it as i have enough contracts with Vodacom, i am trying to save money where i can!. So now i have to waste my time once again and call into the call centre to request that this must be done for the 3rd time now! not impressed especially since i been i loyal customer with vodacom for over 4 years now!!!