I need samples of appeal letters for WLS

Please, I need samples of appeal letters for WLS. BCBS has denied my initial request for approval. They say it is because I do not have '12 consecutive months of Dr. Supervised diet documentation"....Well, I do have 4 years of documentation from my endocrinologist, but they interpret it as he 'suggested' weight loss, and that is not PROOF of Dr Supervised dieting. I do have a request to my endocrinologist for a letter of medical necessity..my insurance plan booklet says "surgery for the correction of Morbid obesity is covered IF it is medically necessary and with Prior Written Approval." Thats all,,,Nothing said about diet, or 12 months of anything............. Any/All suggestions will be greatly appreciated. Anyone else appealed on this same issue? Without PROPER documentation???? (meaning what THEY consider proper...) Thanks Beckey