AWS Blacklisting?

["Justin H." <justindh.ml () gmail com>]

I have a customer who's suddenly been getting 403's today on AWS hosted 
sites.  My google-fu seems to be failing me because I can't seem to find 
any information on who manages that on their side or how to fix the issue.

I've sent an email to amzn-noc-contact () amazon com based on ARIN 
contacts, but it doesn't seem to be a responsive address.

Has anyone had to navigate this particular maze before?

Thank you,
Justin H.