The apparent lack of service from Amazon Seller Support is legendary so I don't need to harp on but for once I would like to share a positive experience.
An Amazon moderator (@Roberto_Amazon) responded to a query on the forum and followed through with constant updates. He contacted the necessary dept and when it was ascertained that an Amazon error had been made, he advised a course of action to fix it. My problem is now resolved.
Thanks Roberto, it’s a breath of fresh air to have someone at Amazon listen to an issue and to then use initiative to fix it, rather than responding with stock answers and ignoring the issue.