You're Billing Me For What?!?

So a few days ago, I received another explanation of benefits for Amaya.  I was not shocked since I'm still waiting on our official hospital statements for filing.  I quickly looked at it, not expecting anything unusual, and placed it on the table.  As I was walking away, the thought occurred to me that something wasn't right.  I headed back to the table to look at it again and realized I was billed a circumcision!!!  My daughter better not have had one done.  The last time I checked, she didn't have "equipment".  This procedure was billed the day we were both discharged and by a doctor I have never met.  So I had to make a few phone calls...my insurance company got a good laugh out of it.  Well, I'm glad someone did because I'm not sure who to be pissed at: my peds office (since it was one of their doctors), the hospital, or insurance company (since that should have been flagged for the procedure, she's a female).  I understand billing errors happen, but how can this happen.