UPSET THAT FEDHEALTH MEDI VAULT DOES NOT SERVE US as expected, after 15years Fedhealth client!

My wife was referred by GP to go do a Cardio exam 27May2019, based on certain diagnosis our GP felt needed more specialist attention. We called Fedhealth, explained the situation and even selected one of the Fedhealth 'preferred' providers from their list, they gave Authorisation number [ ********** 82] and she did the procedure. Now the provider sent us the Bill saying Fedhealth REFUSED FLATOUT TO PAY ANY of that 'pre-authorised' arrangement / [procedure, saying we mus pay, or pay into this new-fangled MEDI -VAULT, THEN ONLY WILL THEY PAY??? What utter nonsense and poor service! I demand a full explanation! I am a very irate and upset client! this smacks of hiway ******* and stinking service!! They take too long to answer calls, the CHAT on website I am now waiting for over ten minutes, this is RIDICULOUS!! PLEASE HAVE THEM EXPLAIN!