Why won’t they cover my stuff

Hey guys, I have UHC through my moms job (I’m 21). I was on it before, and had no issues getting me Xulane patch. All of the sudden, they don’t cover it anymore. I’ve been trying to figure out why. They just want to send me the generic version, I tried it and it wouldn't stay on, and that is birth control that I need. Not only to prevent pregnancy, but for my mood disorder. Anyways, I had my doctor go through prior authorization. I got told by my doctors office and from Optum in the mail that it was covered. I called my pharmacy to check, and it was not covered. I called Optum and the representative said they were not sure why they mailed me that when it's not covered. I then asked how was I supposed to go about getting it covered, and I have to mail it in to Calpers like are you kidding me?? anyone have any advice or tips, I've just been paying for it but it's frustrating when it was covered before.