Vodacom upgrading contracts without concent

Trying to cancel a contract is impossible. Vodacom said I renewed the contract but there is no records of the renewal. For more than a year this is been going on. We asked for the voice recordings or emails where I upgraded but its a lie and vodacom is just billing me for a product I didn't requested. Call Center is *********** to assist in providing proof of upgrade request. Just telling me that I must pay and that's it. Nothing they can do, or my account which I didn't signed up for will be handed to legal department.