I have never in 9 years working with AWS - four at product companies as the architect, 3.5 at AWS itself working in the Professional Services department and the last two working at 3rd party companies - ever heard or read about anyone either on a personal project or a large organization not be able to get a refund or in the case of a large org, sometimes a credit from AWS when they made a mistake that was costly to them.

I haven’t even seen reports on subreddits