Discovery Medical Aid

I went to emergency room on a Sunday to Glynwood hospital which my medical aid cover. The medical aid even gave an authorization number. The doctor there send me for x-rays and did take some blood and also refer me for Sonar, now after the visit the medical aid refuse to pay any of the tests and x-rays and their reason its not the network x-ray or just stating they dont cover the blood test as its not the network doctor, my question how do they expect patients to go to outpatients if they not going to pay after giving a authorization number. Suddenly you also dont have a secondary doctor since January, i feel this medical aid is *********** the patients, what are we paying for as they are not cheap