Wait for you final bill.  This typically comes about a month after you canceled (it depends on where you are in your billing cycle when you cancel).  Thy will calculate a final bill for you.  And if you dont have pre-authorized payments enabled, you will get a cheque in a few months sent to the address on your file

https://www.koodomobile.com/en/help/things-know-about-cancelling-koodo

Thank you for your reply. My address has been changed. How can I change my address info?

If you are able to login to your self serve you can change it there.  But it is unsure if they will use the new address.  You may need to have your old address occupant forward to your new address

I had also mistakenly done this. Koodo ended up just crediting my account the extra I paid which I wish they had just sent my money back. Keep an eye on your self serve and see if maybe they ll do the same. Took a week before I seen the reflection on my account.