I can't speak to AWS, but I have worked with Amazon support for seller related questions and it was a noticeably bad experience, to the point of me completely abandoning a strong business I had been pursuing. I had bought commercial insurance to protect something that I was working on. During the filing process to register everything on the books properly with Amazon, the insurance company didn't have some key detail that Amazon required to be listed on the insurance companies paperwork. I brought this up to them and...nothing.

I contacted them 3 or 4 times about it. I received a scripted response and eventually gave up and assumed that, if I couldn't even get the registration paperwork to go through with Amazon without months of delay, that it's probably better to call it off and look elsewhere. I'm glad I did.

This was also through a fairly well known insurance company, and I suspect that a noticeable large chunk of people who sell through Amazon have improperly filled insurance paperwork, even though there were a bunch of warnings about needing to do it in a very specific way.

The stench of indifference on Amazon's end, and the fact that they were entirely willing to leave a lot of money on the table, has left a very bad impression on me. This isn't even to mention the numerous issues in how they treat employees, artificially raise prices, etc.