Welcome to Cruise Critic! As @jwattle has stated above, simply log on to Princess.com, click "My Account" and then click "Cruise Credits". This is where they should show up. If they do not show up there I would send an email to customerrelations@princesscruises.com explaining what the issue is. If possible, attach a PDF scan of the letter you received. If that is not possible, look for any special "codes" or ID numbers that look like they uniquely identify your letter/FCC and include that in your message.