I understand the frustration of finding specific contact details. For Kindle novel inquiries, the best place to start is Amazon's official customer service page. They have a dedicated section for Kindle support where you can find phone numbers, live chat options, and email support.
If you're looking for a direct line, I recommend logging into your Amazon account, scrolling to the 'Help' section, and selecting 'Contact Us.' From there, you can choose the Kindle option and follow the prompts to get the phone number. Sometimes, the number varies by region, so make sure to select your correct location. I’ve found this method to be the most reliable, as unofficial sources often list outdated or incorrect information.