I'll be trying to avoid @UHC for the rest of my life, or until we get single payer. Here's a brief description of a terrible experience that really isn't that bad in the grand scheme of things.
I was on UHC, had no problems, then got a new job and extended it for one month with COBRA. Hurt my knee (I was on crutches for two months) and paid out of pocket to cover an MRI, bc doc's office didn't have my new card, couldn't run it. I paid knowing I was in-network.
They sent a claim denial to my doctor (not me, as they should have, since I filed the claim). They needed diagnosis codes. I went in person to the doc, got them, and called them in. They refused to accept them from me.