I have done this twice and was wondering if anyone has as well. Have you ever taken the time to visit Customer Service onboard just to thank them for what they do. If you have ever worked in customer service at any level, you will agree that the customer is NOT always right! These crew members take a mistake they have not caused and try to make it right. From missing OBC's, cabins not cleaned to your liking, wrong dining time assignment or extra amenities purchased online prior to sailing that are missing from your folio. None of these issues are the customer service departments  fault yet they do all they can to correct the issue. Many have posted that customer service crew were rude and uncaring when approached with issues. Makes me wonder how those passengers approached the service desk to begin with. Rule of thumb, "Speak as you wish to be spoken to". They are there to help, not make the situation worse. One of the times I went to the service desk to thank the crew there, they were nice enough to send us a tray of chocolate covered strawberries and a bottle of champagne just as a show of gratitude for recognizing their service. Remember, they are people just like you that may be having a bad day, missing home and their families or the guest in line before you may have given them a bad time. 

The second thing I do and still do after every cruise is write a letter to the customer service department at the cruise lines corporate office with a review of the cruise and identified the strong and weak points of the cruise. I never use the "Contact Us" link on the cruise lines website as I feel a written letter is more direct and personal. Although it may take up to 90 days in some cases to receive a written response, they reply thanking me for helping them identify and correct any negative issues and to enhance the positive. Many people gripe about cruises in reviews but I can't help but wonder how many have taken the time to contact the cruise line not only with the negatives, but the positives as well. A consistently poor experience on a ship by various guests can NOT be corrected if not addressed to the cruise line ! There is much competition in the cruise industry and believe it when I say that a cruise line wants you back. Bon Voyage.....