This might be correct!

On the homescreen of the app, we display only the current 'in-use' data plan. If your current data plan still has data or days remaining, it will use those first before activating the new data plan. Once activated, the new plan will appear on the main page.

Note: there might be a slight delay before the new data plans shows up on the home screen. 

You can always find your purchased data plans under 'My plans'.