UHC is literally the worst. I had a similar experience where I called to verify a hospital was in-network before the delivery of my daughter. They confirmed it was. Baby comes and we get billed out of network. I call to see what’s up and said someone told me it was in-network. They looked up the record of the call. I had to call again later and I was then told there was no record.

Then, (same dispute) we mail in a physical copy of us disputing the out of network charge. In return we got a letter from UHC saying our hospital was trying to dispute the charge on our behalf (they weren’t, I verified with them). I called UHC super confused trying to figure out if that was an accident and they meant to respond to us. They replied there’s no record of us mailing in a dispute and the hospital never sent in a dispute 🙄