My mother's doctor billed her insurance, and insurance over paid the doctor.  Doctor supposedly returned the over paid amount, but now has billed her for the over payment.  Logically, I think she needs to get a itemized statement from the doctor.  Then verify it with what the insurance company paid. I understand that she can be billed for service her insurance will not pay. At the time of service I believe she was at a catstrophic level of her insurance.  Am I on the correct path?