Please help

My mother was diagnosed with Breast cancer and the medical does not want to pay for the full treatment of a drug called Herciptin and other oncology expenses. She keeps calling the medical aid to ask the reason and they have told her that it is industry practice, however this does not seem to be happening with the other medical aids. or on a higher option plan of Bonitas. Can we please recieve assistance from admintrators or someone senior who can assist in providing answers to our questions or just pay for the treatment.