I get it. At first I was puzzled with the finely drawn characters and their interactions set in an inadequate plot. Then I thought about "The Loved Ones" and other Evelyn Waugh novels.
This is a well wrought satire of health farms. The main character is a failing menopausal romance writer. This allows the story to have a full blown emotional tinge. The rest of the characters are stereotypes of perfection with failings as in a Greek tragedy. Even to the rescue.
I do not have a reason for the number of people being nine except it works. As does this book on many levels.