After paying all the bills for my surgery, I got another bill in the mail from the hospital. All my 'Explanations of Benefits' matched and yet another large bill arrived that they wanted paid in 10 days. I called Aetna three times before someone would call the hospital. After they talked to the hospital, Aetna decided that they had overpaid and seemed grateful that the hospital caught the error. So guess who gets stuck with the bill?