> After 14 months I got a $7,000 refund. I was told it had to be approved by the head of AWS.
$7,000 of credits is no problem. At that time a friendly neighborhood PM or director could issue the credit without much oversight.
Your problem is the time period. Amending a bill in the same cycle is EZ. Fixing the previous cycle is a PITA but pretty common. Issuing amendments for the previous financial _years_ would be a huuuuge PITA going through finance etc.
Reminds me of working for a cable company and being told that even if we screwed up and stole from the customer the look back period was only a few months and if we found an error from before that we weren't supposed to correct it.
Banks and financial institutions are the same. If they haven’t issued you a monthly/quarterly statement yet, they can just apologize and tell you the numbers are wrong please wait for the statement. But it is a major issue if an actual statement has the wrong numbers.