Cancellation of contract

I recently lost my phone. I am sue for an upgrade in June. I am not allowed a premature contract as it is too early. My only options are to cancel and pay for data and minutes that I am not going to use or take up a second contract. Firstly why do I need to pay for data when prematurely cancelling, should I not pay for the devise? Secondly why cant we prematurely upgrade and pay what needs to be paid? after many years of being with Vodacom, I have decided to cancel and move to another network as options are very limited