I bought 3 paintings @ auction on a norwegian cruise, they sent 2 and won't send the last 1, what do I do?

I bought the paintings at auction on the cruise. They are all by the same artist, and the one that I really wanted has not been sent. I received a letter yesterday from a representive of Norwegian cruise lines informing me that they are not going to send the last painting and that I should call my credit card company and tell them there is a discrepency on my card.They gave no reason for the sudden change. I want an answer for this companies poor customer service, and dare I ask an apology. I am frustrated and I don't know or how to fix this or what to do. Please help and give me advice on how to handle this. Thank you