The first time I was double charged at a doctor's office, I wrote it off as a fluke. A clerical error caused by a complicated insurance system.It was mildly bothersome the second time, but I still told myself it was more gaffe than scam. When it happened a third time, in barely more than a year, it felt like something entirely different.It felt like I was being hustled.What we're talking about here does not rise to the conventional definition of fraud. It's more like blissful ignorance. The more ignorant the patient is, the more blissful a doctor's bank account gets.To set the stage for you:My insurance plan comes with a health reimbursement account. Basically, it's a pot of money that pays for doctor visits, tests and other expenses that help pay down my deductible.In each of the three cases — an eye doctor, a dermatologist and an ear, nose and throat specialist — the office insisted that I pay a fee on my way out the door. In each of the three cases, my health reimbursement account later paid the exact same fee.And the doctors' offices never bothered to notify me.I suppose, if you take a caveat emptor view of the world, you might be able to rationalize this double dip. After all, it's my health insurance, so it should be my responsibility to recognize who gets paid what.It's just that — call me silly — I expect more of doctors.You can't tell me that bookkeepers at three offices were not aware of the discrepancies. We're not talking pennies here. One bill was just under $200, another was just over $200. If, instead, I owed that much, I guarantee you the bills would have been in my mailbox.At some point, these offices had to be aware they had been overpaid, and yet they did not send a refund. They didn't pick up the phone to let me know. They didn't send a balance sheet showing a credit.Instead, they kept my money and they kept quiet.Illegal? Probably not. Unethical? That's debatable. Unsavory? Heck, yeah."I don't know if I would call it unethical or just falling through the cracks,'' said Candice Butcher of Medical Billing Advocates of America. "But I know we often see cases where instead of being refunded, a patient's money just sits in the system.''In two of these cases, I waited months after verifying my insurance payment just to see if the doctor's staff would finally get around to contacting me. They never did. When I did call, they acknowledged the overpayment but never had an explanation as to how it could have gone unnoticed for so long.The potential fleecing bothered me, but not as much as the implications. This has the whiff of a shell game, and I worry about senior citizens who might be too trusting to question a doctor's office.Now this is obviously a small sample size. And I know doctors often have a difficult time with insurance companies and unpaid patient bills. So I'm not trying to use a broad brush to indict the entire medical field.But three different examples in such a short time should be a warning sign to anyone who assumes a doctor's office isn't a business first.If you've been in enough of those offices, you've surely seen some variation of a sign that says payment is due at the time services are provided.So here's my question:Shouldn't they have the exact same attitude when it comes to refunds?