My insurance says I owe nothing, so why is Quest Diagnostics demanding $563?

My insurance says I owe nothing, so why is Quest Diagnostics demanding $563?

I had routine blood tests at Quest Diagnostics last year. My insurance company, Lucent Health, sent me an explanation of benefits stating "Patient Responsibility = $0.00." I thought everything was settled. More than a year later, I received a letter from a collections agency demanding that I pay $562. When I called my insurance company, I discovered a second explanation of benefits that...