Contacting KDP or Kindle Support
If you need to contact KDP support, login to your KDP seller account and scroll all the way to the bottom of the screen where you'll a tiny 'Contact Us' link:
Need Kindle (Device) support?¶
If you need help with your Kindle device, contact customer service at 1-866-321-8851 or (206) 266-0927
Did we send you a new Kindle eBook file?¶
IF you loaded the mobi file on an eBook reader manually, you should delete the old file first.
OR
IF you purchased it from Amazon, they will need to remove the file from your device and deliver the new one after it's published. Here is a link to the customer support page.
OR
If you are requiring KDP (Kindle Direct Publishing) support, the only option is to either contact them through your KDP account (click on the 'Contact Us' link at the bottom of the screen) or contact Author Central. If the agent at Author Central determines he/she needs to contact KDP technical support, they have the means to do so.