I stated that I used the address once to complain and once to praise. The complaint was in regards to a specific assistant cruise director and the derogatory comments he made in public. I did not ask for anything in return for my letter. I simply wanted them to know what happened and how much his comments had left a bad taste in my mouth at the end of a wonderful cruise. I wrote the letter much the same way I would complain to a hotel manager if one of their assistants had made the same type of comment. To me, it was to inform them.
Having written that letter I felt it was only fair to write again when one of their employees did something above and beyond for my wife and I on a cruise a couple of years later. This was not a ship employee, but one who works in the airport assisting passengers.
Each time I recieved a nice letter and a future discount. I only used one of the discounts.
As much as I love Carnival cruiseline, I believe that if they really mess up, they need to know and when they exceed expectations they should likewise be informed.