PAYMENT OF MEDICINE

I am a Diabetic and i am on the Keycare Plus Plan I went to a Dr. and got a prescription for my medication i then went to a chemist to get my medication and tthe medical aid declined the payment for this i thought if you go to a designated chemist then the medicine will be paid but no i then phoned Discovery and they told me none of the medication will be paid if it is not registered on chronic not all the medicine is chronic only the Insulien and blood pressur pills.WHY???????? So that means if i get a description for any medication i first have to register it before it gets paid by Discovery it just does not make sens to me i thought if you use the Network Dr's and the Netwrok Chemists then they will pay it for you.PLEASE EXPLAINNIT TO ME AS I AM DUMBFOUNDED AS THIS MEDICATION I AM USING IS CRITICAL TO ME AND I NEED IT FOR MY SURVIVAL.