"When you get a credit from a cruise line or airline, for whatever reason, they are usually only good for one year. So, what happens when you want to use the credit but can't due to a very serious illness?
Princess says they stand firm to the one-year expiration dates on credits but if you do have a valid health issue they will look at those requests on a case-by-case basis. One other tip: When presenting your case in situations like this, have your doctor write a letter to the cruise line as added proof of your health condition."
http://www.azcentral.com/12news/consumer/articles/2010/03/09/20100309Princess-Cruise-Credit-03092010-CR.html
