Discovery full of lies and denies claims

Discovery has been making excuses to not give me authorization to get a cosmofer drip, they said I should see a GP on the panel and then the GP suggested to go see a specialist, the appointment is next week and Discovery went back on their word to pay. Initially my GP and my Specialist gave them all the documents and they made an excuse, now I followed their procedure to get the problem sorted and they own network GP told me what to do and they refuse. Discovery staff at the authorisation department are useless.