How can they do this to me operation done but now it looks the medical aid does not want to Auth for the stuff to be removed

I must say fedhealth is so stressing me out I had a kidney stone removed yesterday. To day the doctor called me to advise me that I have to come back next week the 17th to remove all the drainage pipes. I called the medical aid department now and they advised me it's not going to get authorization. (please can someone help how can the medical aid say they can not help me the operation was done but now they do not Want to pay for the removal of the stuff that is still in me. Really please can you look into this please my ref is ********** 61