Constantly Rejecting Valid Claims for flimsiest of Reasons

I have been with this medical aid for a number of years. I have submitted multiple valid claims. EVERY SINGLE time a claim is submitted I then need to spend hours on the phone for days to call centre agents and then escalate to management to get the claim rejections resolved. They reject claims on the flimsiest of reasons - e.g. I obtained valid authorisation for a day procedure in a hospital. Then the claim is rejected because the procedure took the whole day in the hospital! Then when you query and escalate - it's suddenly resolved! Keep away from this company - unless you want to raise your blood pressure and cell phone bill!