Forfeiting available balance when upgrading to a top up contract?

<p>I would like to upgrade my prepaid line with Vodacom to a topup contract but wasinformed that they availible balance whcih is about R1200 will be lost when I upgrade. I reuse to believe that there is nothing Vodacom can do to have this balance transfered to a contract. Why would Vodacom loose the opertunatly to sign a new line and upset a customer over something that is mine which I paid for. Am Ibeing difficult in refuses to loose R1200 worth of airtiime or is there some one emplyed by Vodacom that can I understand where I am coming from an is willing to assist me?</p>