non payment of chronic or generic of chronic-Bonitas

Please can people be aware of certain things on this medical aid. My child is on a chronic medication for asthma. It was covered by previous medical aid. Bonitas rejected it saying it is not on their formulary. My gp says there is nothing on their formulary that is similar or a generic. They are literally dictating as to what class of medicine my child must use. This is the one that works for her! If it's too good to be true it probably is.