We actually got a free 7 day cruise for two from RCCL.
Some of you have heard the story, but short version is the stevedores in New Orleans dropped my luggage overboard and it sank. Problem was they did not fess up to it for 2 days and RCCL told us our luggage would meet us in Cozumel, then Belize . . . etc. Finally they told us what had happened. During the cruise we got a lot of attitude from the purser staff and two bottles of wine. Oh, and $150 credit in the gift shop. Problem was the shops are stocked every other week anf this was week 2 so there was very little tochoose from. I did get a tshirt, pair of shorts, flip flops and a bathing suit. They loaned me formal wear although I had no stockings (I just can't stand to wear heels without hose)
We were never ugly or rude. Hey, it was a cruise and it got to be a big joke that I was "neck'ed on the high seas". People would actually buy me drinks (can ya' believe that?). Life's too short to be ugly unless it's you're only option.
When we got home I wrote a very long and humorous letter to RCCL asking the gents in charge to imagine life with a woman in the same clothes for 7 days in 100 or so square feet.
I thought they would give us a discount on a future cruise but was amazed when they gave a free cruise for 2. WE used it for our first sailing on the Adventure of the Sea and they gave us a fabulous cabin and a bottle of wine! Kudos to RCCL
Contrast that to NCL (my favorite line actually).
We were sailing the Dream to the Baltic capitals and have a 2 night hotel package, pre-cruise in London. We had guaranteed a late arrival (very late since we weren't arriving til 6 AM) but when we got to the hotel they were full so they gave our room away. We had to wait til almost 3 PM to get into a room.
When I wrote NCL they said there was nothing they could do since hotel stays are out of their hands. Hmph. Considering the cost of hotels in London it was a nice chunk of change. Oh well.
I think the key is to be clear about the problem - no whining, be nice and humor helps, include names, depts, etc. if possible.