Roll-over data has been suggested before by a Mobile Master and many others in the past. I completely agree and it makes perfect sense. Unfortunately, it appears as though Koodo is not interested in going that route at this time.
So if you want your idea to have more power, please use the "SEARCH" button to find the other idea an support it. One BIG idea with a lot of support is better then 50 with only 1-2 people supporting it!