Speaking from my own experience, with a much, much larger bill: AWS support will most-likely ask you to set up the cloudwatch alarms and billing alerts properly

Speaking from my own experience, with a much, much larger bill: AWS support will most-likely ask you to set up the cloudwatch alarms and billing alerts properly, and to provide a plan to mitigate further issues. Once you've done that, they will be more inclined to reduce the charges.