Not happy at all

I have read through other complaints and noticed I am not the first person unhappy about this. I have been a Vodacom prepaid client my whole life and recently switched to contract. I did my application online, a process that was very efficient. That is until recently I was informed that I have to pay an extra R9.50 each month to allow me to see the caller ID of people phoning me. I don't mind paying that money each month at all, I mean it is nothing, but it is simply a matter of principle. I asked the lady who did my contract over the phone repeatedly if there were any other costs involved each month, no matter how small, apart from the device and airtime, and every time she reassured that there were no other costs. I feel it is terribly unfair to give a person certain information, ie regarding costs, to encourage them into taking out a contract and then adding other costs afterwards that were never mentioned. <br> <br> Please explain how this is possible and why this rate does not apply to prepaid customers as well, but only loyal contract customers?