I was actually successfully in reversing a $500 AWS bill. I had needed an Active Directory domain controller so I found one in the AWS marketplace and deployed it to an EC2 instance. Well guess what, the DC must have had some malicious start up scripts in it because it proceeded to download a few TBs of data from outside to the AWS EC2 instance which equaled nearly $500. I complained and AWS immediately reversed it without any need to escalate. This was on a personal AWS account so no relation to any large organization. Morale of the story, dont trust AWS marketplace images from sketchy sources.