Pain control treatment not authorised

My daughter has a chronic pain condition and was expecting a terrible flare that she could not control with her usual pain meds at home. She was authorised and admitted for pain control treatment. This is typically 3-5 days. However, her pain was not under control after 5 days so she was treated for 8 days. Now Discovery is refusing to pay for the 3 'extra' days. My daughter was in a severe pain flare- she needed extra days. Her specialist has sent letters explaining this but Discovery refuses to pay.