I ran into the "saving of chairs" problem on a Bermuda cruise last year. Here is how I handled the problem.
Since I have fair skin, I cannot sit in the sun all day on the deck. I proceeded to look for a deck chair in the shade and I noticed two older men sitting on chaises with approximately 15 chairs down from them completely empty with the exception of a few that had only a towel on them. I proceeded to sit in the middle of these unused chaises and the one man screamed at me that that chaise was saved. I got up and moved to another one where he proceeded to scream the same thing. I sat down unnerved and told him that if they were saved where were the people they were saved for since they had been vacant for quite awhile. I told him if his people came I would get up since I can't sit in the sun all day. He then said I had quite a nerve. I mustered up my courage since he really had got to me with the yelling and all and I told him that there is no policy of saving chairs and if he didn't like it he could get someone of authority to tell me to move. No one came. This same man and his party incidently went up to the midnight buffet (about 30 people with him and about 45 minutes after it started) one night where entertainment was provided on deck. I saw him inform the head person there were no chairs and he complained until she had the deck persons go somewhere else to find him chairs. It takes all kinds. I guess some people feel that they pay their money and that entitles them to be rude and to treat people like crap. There was no way I was going to let him speak to me that way.