Anthem-COVA Help!

Hi everyone, I am wondering what do you do when insurance will cover one procedure but not the one you need? I have such a time crunch to have this done. I need to have surgery in the second week of Dec. So, I really don't have time to appeal. Is there any suggestions on how to approach this. The insurance covers the procedure but because they consider me a light weight -lol- I have to settle for a less effective surgery for me. I'm sorry to sound so frustrated but I don't know what to do. Any suggestions would be great! Thanks