Amazon has changed how you can update your Kindle Books. You no longer need to go through Amazon customer service to update your ebooks. You can simply log into your Amazon account to see a list of your Kindle content.
Content that has been updated will be marked with “Update Available”. To get the updated content, you can click the “Update Available” link or use the Action menu on the right hand side of the screen to have it delivered to your Kindle devices.
Old Outdated Tip: Sometimes an author will update or revise the content of their book. Unfortunately, Kindle users who have already downloaded the book will not be able to access the updated version unless they send a request to Amazon’s customer service or firstname.lastname@example.org. When making a request include the book title, author and ASIN. Amazon will then manually send the updated content to your Kindle. In the future, Amazon might add an option to do this online.
Special thanks to ecaggiani of Kindle Boards for contacting Amazon and sharing the original tip.