Vodacoms new data structure is a cheat

I needed more data on my phone so I decided to purchase a data bundle with my airtime. Like I usually do I selected 30 day data bundles and selected a 500mb. Then I get a message saying I have 250mb and an extra 250mb night owl. There was nothing in the menu to indicate that this was the case it merely said 500mb for 30 days and when I have done this before it is just data for use any time. I will never be able to use night owl data because I am never awake from midnight to five am. It is an absolute cheat that Vodacom is trying to force you into using their network during off peak hours. They should at the very least inform their customers (which I have been one for almost 11 years) of changes to their pricing plan.