False Authorizations

I would like to rise a complaint as i phoned momentum for authorization and explained that my GP had referred me to DR Harlies i gave both practitioners practice codes and where they were situated they gave me a pre-autherization weeks in advance just to tell me a month later that i need to pay it myself how does this work..?? i am Really unhappy its unacceptable and the code they wanted the practitioner to use is ******* ********** then the 2nd excuse was that it should have been done in state hospital when my direct words stated it was done in DALVIEW HOSPITAL AT A SPECIALIST!! Now there is a bill that needs to be paid and the medical aid are just refusing saying the authorization does not work even though they gave it to me how does this medical aid operate??