Claim inconsistency

I phoned Discovery regarding a claim that was not paid. They told me the reason that they will not pay my claim is because I need to get a reference for the doctor that I took my son to. The reason that I am upset about this is because I went to a Pediatric Cardiologist for my son earlier in the year and before I went they said I don't need any authorization before I go as he is still under 2 years old. Then I went to another Pediatric Cardiologist 30 June I get a message saying that my claim is not paid because I need a reference number. My only question is what changed from the first claim to the second? My son is still under 2 years old he went to 2 different Pediatric Cardiologists for the same condition and the one was paid out and the one is rejected even though I still had specialist benefits available? I have spoken to 4 different advisors and none of them give me the same feedback, I feel as if claims should be consistent and not a case where Discovery can choose which claims they want to pay and which not. I asked to be called back today as I did not have a lot of airtime and when the phone dropped while I was on the line with a consultant he didn't even bother phoning me back. Pathetic service does not describe how I feel currently.