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.
46 Cruises & Counting! Favorites: Paul Gauguin to Tahiti: Uniworld River Cruises in Europe; any of the Celebrity Solstice-class ships; Holland America for 12-nights in the Baltics & Russia; RCCL for 14-night Greek Isles, Turkey, & Croatia; Holland America for 14-day Alaska cruisetour; 10-night Canada/New England cruise; 21 days in Hawaii including a 7-night NCL cruise; Oceania for 25 days in Asia; & 3 months touring Europe by train. And many days spent in all-inclusive resorts!