It never fails; I always receive the doctors bill and when I check the bill against the insurance explanation of benefits statement; there is an error!  Frustrating for sure.  Either the doctor overbills or the insurance carrier doesn't pay the claim correctly.  Case in point- had a annual physician w/ob-gyn.  The insurance coverage allows for one such exam in a year so no problem.  Get the bill; DENIED???  Call the carrier; oh the doctor didn't use the right code to bill.  Call the doctor; nope the right code was used the carrier is wrong.  Call the carrier again; yup- Doc is right the carrier has a "system glitch" with the code and it is being sent for adjustment.  4 weeks later; another denial from carrier, another balance due statement from Doc. 

Frankly, this would exhaust the average consumer right? 

The point is you have to check all your bills and EOBs before you pay; don't assume they are correct! 

OH YEAH...after 4 months the bill got paid in full to the doc.  Just took 4 months and loads of my time; wish I could balance bill them for that!