Cancellation Policy

I am appalled by Vodacom's cancellation policy. I have shared my interest to cancel my vodacom contract 11 months early, and they are insisting I pay for the remaining minutes. I have no problem paying for this, however should I actually go ahead and cancel early, my number will be moved to prepaid and I will not receive the minutes and data that was paid for. How can I pay for something I will not be receiving. I do not think this is fair at all. Now I should wait out a contract I would have liked to settle early. This is horrible services.