VODACOM - Frustrated after contract activated

<p>Hi. Recently took up a data contract (just data as I have a device). After initial issues resolved, the contract was activated. Data contract on an open line. I need to know how I will be billed for calls (as I do not want this being taken from my data nor do I want another contract - which is what all the agents suggest). I want to be able to make calls and Vodacom can bill me seperately for this OR i want the option of making calls and purchasing airtime whenever I need to do this. I have been told I cannot do this due to the open line - which is ridiculous. MTN offers their customers the very same option I am requesting yet Vodacom apparently does not. I have just begun this contract and am already regretting it. If anyone is able to assist please do so. Again I DO NOT want to take up another contract NOR do i want to switch back to prepaid. I want to use my data contract for data. I want to be able to make calls without my data being used. </p>