Hospital authorization refused

As a member with Discovery forever and now I have to go to hospital Discovery refuse to give me an authorization to be admitted, they claim a day hospital does not fall under their hospital cover, I gave them my ICD-10 codes wich is for a bone biopsy to be done, I was refuse codes at all. Do they want my doctor to cut to the bone in his rooms? Why do I pay medical aid and are not able to be admitted in hospital