The quickest way is probably to visit a Koodo kiosk. A rep there should be to provide you either a blank postpaid or prepaid SIM. You can later change it in selfserve or ask the rep to do it for you. 

If it’s a postpaid account, follow the instructions below to perform the sim swap:

Updating your SIM card in Self Serve

Note: To protect your privacy, this transaction can’t be done over the phone with the help of a rep and must be completed online through Self Serve.

1. Log in to your Self Serve account.
2. On the Overview page, click Self Serve and select Mobile services from the drop-down menu.
3. Select Change your SIM card.
4. Enter your new SIM number in the text box and click Continue.
5. A 5-digit verification code will be sent to your current phone. In case your SIM is lost/damaged, the verification code will be sent to another line or to an email address on your account.
6. Once you’ve entered the verification code, you can now insert your new SIM card into your phone. Turn the phone off and back on again. Heads up! It may take up to 15 minutes for your SIM to be activated.