Best answer by Mats
That was pretty nice of Koodo to give you a break and give you 30% back. In the future you have a few things you can do so data usage doesn't happen again if you didn't already have Koodo do it for you.
Turn data off.
Get the data block add-on on your account. It blocks all data but will allow MMS for $2/month.
If you don't want data off completely, go into the settings of your phone and turn off WiFi assist(iPhone). If it's an Android you'll have to find the box to uncheck 'use data connection when WiFi signal is low' or something close to that depending on what phone you have.