I had my lapband in 5/2001 and didn't have issues with it until 7-8 years out. I did have a slip once but an unfill worked to correct it.
I did have the issues you describe plus gastritis, GERD...my surgeon requested the band be removed, not because of band failure, but because of the medical issues I was experiencing as a result of the band.
I'd definitely appeal the denial...and see if your surgeon can conference in with your insurance company to discuss the matter...let him explain the medical issues you're experiencing....have him sight statistics, or whatever....but, definitely APPEAL.
If you want an excellent attorney to handle your appeal, contact Walter and Kelly Lindstrom at obesitylaw.com. They were instrumental in getting my lapband approved in 2001 after it was denied initially.