How to get my insurance company to reconsider their denial

After I went to the seminar for Lap-Band I came home and called my insurance co to see if they covered Lap-Band procedure.  They said yes but I had to do all the things they required, 6 month supervised diet, dietary eval, exercise eval, psych eval, 5 years of medical records to prove I've been overweight at least that long. Ok, so I did all that.  Sent my paper work in and they denied it.  At first they said I did not have my psych eval in it, but then they found it.  But it was still denied.  they said it was medically unnecessary.   I have a BMI of 43, diabetes, high blood pressure, arthritis, depression, Now the insurance co is telling me that THEY consider it experimental surgery.  Even though it is FDA approved THEY STILL consider it e xperimental. Is there any way around this?  I'm planning to appeal but I want to make sure I have all my ducks in a row before I send anything to them.