In that case, you can log in to your Manage My Kindle page, click the Settings option in the top-right portion of the screen, click the Automatic Book Update option, and select whether to have updated books automatically sent to your library.

BTW, you might want to call back Kindle CS and tell them the book uses a blue-green text which results in a very light grey text on Kindles. It might look good in print or even on a tablet, but certainly not on a Kindle.