Have your agent call to see exactly why you got the amount you did.
From what I was told it was based on the cabin type you were in. In other words, the certificate was suppose to be good for a free cruise of equal amount and it would not be fair for someone who paid for an inside cabin to get the same amount as someone who was in a suite.
Travel Agent/Cruise Specialist w/12 yrs exp and 47 Cruises on 11 cruise lines! Favorites: Paul Gauguin - Tahiti: Uniworld River Cruises - Europe; Celebrity Solstice-class ships; Holland America - 12-nights Baltics & Russia; RCCL - 14-nights Greek Isles, Turkey, & Croatia; Holland America - 14-day Alaskan cruisetour; 10-night Canada/New England cruise; 21 days Hawaii w/7-night NCL cruise; Oceania - 25 days in Asia; more than 3 months touring Europe by train. And many all-inclusive resorts!