Yup, last employer had me on a different plan then I signed up for. Went round and round with the employer and the insurer. Of course it was the others fault.
Finally talked to DoL guy and they told me it's absolutely the employers responsibility. They kept going back and forth with me. This was about and $1800 difference in out of pocket max, not in my favor...
Finally they fixed it, but only for my wife. Since she had the majority of the bills due to a surgery, the insurance clawed back a bunch of smaller stuff they had already paid. So that cost me about a $1k. I guess I'm going to have to sue in small claims, which is what the DoL guy recommended.