Welcome to the community!
You should be able to retrieve your PUK code from your My Account --> Usage & Services --> Mobile. From there, you would need to select Retrieve PUK code (near bottom of page under Quick Actions).
If you are unable to retrieve your code that way, you would need to contact customer service. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
Hope this helps 😀