Prosthetic microprocesor knee

Hello , In may of 2000 I was involved in a serious motorcycle wreck, I lost my left leg above the knee and my wife of ten years. The wreck left me unable to work , since then I have been on disability .
The  prostetic leg which medicare only pays a small portion of is in need of replacement. At this time I am on a lender knee untill my prosthetic company finds out if medicare will pay to replace my unit.
  I am a high activity level amputee that would benifit more with the Otto bock cleg 4 microprocessor prosthetic leg . Visited my prosthetic company today 6/16/15 , Medicare has agreed to pay their 80% for 
The   Otto bock cleg microprocessor prosthetic leg , I  have to pay 20 % which is $7000.00
Any help towards my goal is very much appreciated.
Thank you..