I assumed you are a postpaid customer?

If so, have you checked if your account had easyroam added? https://www.koodomobile.com/en/easyroam

Also, when you travelled, you were relied on Koodo roaming partners - not Koodo network. Their network availability depends on where you are, your phone and network bands. 

The Easy Roam feature is triggered automatically if you make or receive a call, send a text message, or use data on your phone. I would suggest you to wait until your next bill to see if it shows up. Otherwise, there is nothing else you need to do.