I too have suffered the Accor disadvantage plus membership. I lost my first free night as they had given me the membership number of another unfortunate member. By he time this error was rectified I lost my "free" night. I have had similar experiences trying to book nights the web site says they are available but they suddenly vanish when you try book them. I am making sure I never stay in any Accor hotels in future. I advise anyone reading this to use any of the other more reputable hotel chains such as Hilton, Radisson and Sheraton etc. Please advise everyone you know to take their business elsewhere.