Discovery medical aid

Can someone help me understand, I’m currently on Above threshold Benefits and have R23 498.00 funds but yet my medical aid can’t pay for R647 medicine. It’s almost end of the year and would like to know when will I use my Above Threshold benefits and for what treatment. I feel ****med and will definitely change my medical aid. I stayed on a call for long with no better explanation as to why they can’t pay now but last month they paid for the same medicine without a problem.