An update: since contacting the author, I've received 3 separate replies. According to the first one, a family member who handles the author's PR is responsible for reposting the review and I was promised it would be removed at both bookstores ASAP (and that these are only places it was posted).
The second was an
update message, to let me know one review had been removed and the other may take longer to be gone. The third was to inform me that the review was removed from the second store. I've since confirmed that it's been removed from both stores. However, the user accounts (in my handle) remain …
The tone of all three messages was appalled that such a thing was done, apologetic, and eager to make things right. For my part, I'm just relieved the situation is resolved but I'm left wondering if the reviews (for this book) of other GR users were lifted in this way.
Thanks for all your advice, which helped me deal with this in a calm and assertive manner