Claims not paid with no valid reason

Discovery really is pathetic when it comes to paying out claims. I am a healthcare provider and have had numerous incidents in the past. However the most recent one being a psychological consult from the maternity benefits has not been paid - 6 months later. I have followed up numerous times and each time I am told that the benefits are applicable and they are resubmitting the claim but thereafter, I get no feedback and the claim is not paid again. Last week I called and demanded to speak to a manager - the manager called but guess what - still not feedback and still no payment of the claim. Discovery is literally the worst paying medical aid ever!