Comment Far from the worst error that could occur. (Score 1) 20
Obviously billing errors are bad; but it seems like ones that off by an egregious number of powers of ten should concern us much less than ones that are small enough to be within the realm of plausible; those are the ones that you'll need to fight over and quite possibly not even win if you are an edge case or dealing with one of the services/configurations where you don't necessarily have any independent measure of usage. You can probably tell that you didn't use a VM more than 720 hours in the last 30 days; but are you actually counting GET requests in some way that is both authoritative and cheaper than just paying the $0.0004/thousand rather than hoping that Amazon will charge you correctly? For some very buttoned up buckets that only your other stuff accesses, quite possibly you can infer from those systems; but if it's something public facing and it might be a billing error or maybe you just got crawled hard last month?