Authorisation for CT angiogram

I phoned for authorisation on Friday (25 October) for a CT angiogram. I was told that I need to send a motivational letter from the doctor. I sent the documents that the doctor gave me on Sunday night, however I have received no feedback yet. I find it shocking that I need a motivational letter for a scan when the doctor has requested it. Why would the doctor request one if he had no reason to send me for one. I've been for multiple MRIs this year and its never been an issue. To top it off, Momentum either pays nothing towards any medical bill or minimal amounts. What's the point of having medical aid if nothing gets covered? Pay premiums and get nothing in return.