Corus spinal system Insurance approval

I've had two fusions C3 and C4 and C5 and C6 but the C5 and C6 failed which has caused me severe pain and a lot of physical therapy now they want to do a corus spinal fusion for C5 and C6 but I can't get insurance approval they said it's not necessary we went through the appeal process but cohere health/ Humana denied it has anyone else had this problem