Well, for the book A Million Little Pieces anyway. I just read the article by About.com's Mark Flannagan about the refund for this book. Interesting stuff. If you bought the book and feel horribly upset and perhaps have developed a psychological disorder as a result of discovering that the book is more a work of fiction than fact, just get a refund by tearing out page 163 (hardback) or tearing off the front cover (paperback) and sending it in.
...As long as you bought the book on or before January 26th anyway, which is when the news got out about it perhaps not being a truthful memoir.