Misleading Wi-Fi bundels

Always using my phone as a hotspot to work from home I was informed that a cheaper wi-fi bundle is now available. After buying and trying to connect I realised data is still being used and not the wi-fi data. No where it is explained how to use or explain this new option. Menus are very misleading and now I am stuck with 2gb and less R100. It might not be much to others but is sure is to me. I find it very poor that all vodacom has to say is that they can't exchange or reverse the order!