The website has been giving this error message to many people over the last few months. Your only option is to call customer service who will issue the PUK to you.
You will find the phone numbers using the link at the bottom of the home page.
Many people mis-read that message. It doesn't say that the automated service can't find your PUK because you aren't a customer. Its two seperate sentences. Personally, I would like to see them rephrase this.
They seem to take it down during the evening as they are still working on the current website during the evening. Many pages are unavailable overnight.