Continued claim rejection for a benefit expressly provided for

I am calling on Dr Sinazo Mtimkulu to stop hiding behind call centre agents. Dear Sir. I have an authorisation from Discovery signed personally by you granting a sports injury benefit. Your letter expressly states that I am entitled to 4 biokinetist visits as part of this benefit. The letter provides the codes that must be used. HOW COME MY CLAIM IS BEING REJECTED - REASON "YOUR POLICY DOES NOT COVER THIS BENEFIT"??? Please help me to understand this. I have been phoning and am now onto my 5th reference number and I keep getting the same reply. This is insane and despicable. Discovery has gone to the dogs!