Vodacom fail to process cancellation

I subscribed to a new service after receiving a telemarketing call. Upon delivery of the goods involved I realised it was not what I expected. I called Vodacom and cancelled the subscription within the legal cooling off period. The cancellation was not affected and I received a bill for it. I called a further two times and got confirmation from the agents that the cancellation was done. Despite this the subscription remains active and I still get billed.