I just reached 100% data and got the notification.
The notification states type Yes to add 100MB for $5. But I seem to recall there's a way to add 1GB for $20. Searched the community forums, and didn't find a way to add 1GB for $20 (after looking through a lot of old posts). Called Koodo and after waiting on hold for a while, the helpful lady found out, there's a link at the bottom of the notification to add 1GB for $20. She directed me to turn off wifi, then select the link. [b]BOOM...there it was.
Perhaps this How To could be pinned to the top of the Community forum as a sticky for others to find?