Stop promising what you can't deliver, I want my voucher!

I upgraded my contract with vodacom after being convinced by an upgrades consultant and with the new upgrade I was promised a retail voucher but guess what, Its now the 3rd month and I still haven't received the voucher. Why should I have to run after them to do as they promised??? The call center keeps saying they can't assist coz I called the wrong department and last month after making several enquires I was promised I would receive it but I'm still waiting. So disappointed xem!