Inflated premium on KeyCare Plus cover

Discovery Health debited my account R2588 for a keycare plus medical aid of my son who is financially dependent on me and placed under KeyCare Plus. He had no income except a variable allowance that I provide to him of less than R2500 a month. I don't know how Discovery arrived at a Premium of R2588. When I called Discovery a consultant named Chane' dropped my call twice and the third she just put me on hold and never uttered a word for more than 10 minutes. Disgusting and lacking pride in customer service.