Pathetic Chronic Cover

On 23 July 2021, Discovery sent us a new approval letter for my son's chronic condition for epilepsy. The approval indicated that he is approved for one EEG with Special activation. However when I put through a claim for this type of EEG it was not paid. The initial enquiry via email sent on 4 September was ignored, today when I call them they said to me this cover is only applicable to a new diagnoses and that they will not pay as my son was already epileptic when we joined the scheme. My question to them was why did you include this cover in the approval letter if you know you will not cover it for this patient? They said I can appeal their decision. I need to understand if the approval letters are just blanket answers and pre-populated for anyone who applieas for chronic cover for a specific condition. If my son is not elegible for this cover why include it in the chronic medication cover letter in the first place? In addition to the epilepsy, my son has mental health issues which discovery also refused to cover via chronic and for this exclusion they did not even offer sufficient reasons. What exactly does discovery cover? We pay doctors to fill in this forms you send us, we cant always be appealing after you don't approve the medication/medical procedures!