Not covered under my Scheme

Hi got a knee brace prescribed to me, to prevent a knee injury to the acl I had repaired last year. Discovery now refuses to pay out or even consider reimbur*****t of any sort, my claim has been turned down. This brace was very expensive, and was supposed to be paid out of my savings. I cannot understand how you simply refuse to reimburse anything and also claim it is not an external medical device. It's extremely frustrating as there is endless red tape, had I known all of this, I would have rather ordered the brace through the supplier at a much lower cost!