Amy,
Thank you very much for your response. It looked like I have no way to know what the reinbursement should be.
My first phone call to the insurance company was pretty lengthy, the representative is very nice, she went through all the records, then told me that the code they have used for the initial 10 treatments was 99183 (hyperbaric oxygen treatment) but they have used another code (hospital service ?) for the final 10 treatments, so it caused problem. She agreed with me 100% that for the same hyperbaric oxygen treatment, 99183 should be used for all of the service.
However, the insurance did not adjust the statement. When I called again, the story changed, they said that correct code has been used for all the treatments, but
they have mistakenly used the "old" provider contract for the initial 10 treatments.
So far, I have made about half dozen phone cals times regarding the issue, talking to several representatives, spent long time explaining to each one of them of what had happened but always got a different answer, that is why I started question what should be the correct answer.
I guess if I was overcharged consistently from the very begnning, I would have paid the bill without any doubt. Right now, I know there are discrepancies, and the story kept changing, it is quite frustrating for me being unable to find out the truth but to believe whatever I was told.
Thanks for your help