OP- I can understand your reluctance to "out" them, but I wish you would reconsider.
I feel like you have been very fair in your descriptions of what has (or has not) happened. Your posts are not accusatory and your tone has been much kinder than what I might have been able to muster in the same circumstance.
If you post a "Bewares" thread, you may find others in your same situation. Or, a whole host of their authors may come to their defense. You can't really know if it is a lack of effort on their part unless you know how other authors/books are doing.
Whatever you decide, I wish you the best of luck in upping those sales numbers.