If I try it in the app. - Services - Data Bundle Rollover - with no airtime loaded, it states :The first one is free .
"You do not have any active data bundles to extend. - far as I know, I do - part of the original 50 + 50 I bought & loaded. You can purchase data bundles via the Buy section of the app."
That's why it's confusing
@Cell_C- More explanation required as to how rollover in my real-life example given above, can work?
I've read the points in the link you pasted on" rollovers", but they don't help with the 1x free option.