I've just gone through a similar experience, and to add to the fun, one of the insurance carriers also stated that they would not do coordination of benefits. Being somewhat ignorant of the vagaries of insurance, I just thought that meant that we would have to file ourselves with the second carrier, once we got an EOB from the first carrier. Wrong!!!!!!
It apparently means, at least they explained it to me after many phone calls, that they would not pay. Even if we filed, they would not pay. I asked them why I should be paying their rates then, if they would not pay, and they said I shouldn't, but if I chose to, I could, but they still wouldn't pay. This was on my DW, since she had coverage from her former employer, and I was carrying her on my policy as well.
I don't understand how this can be done legally, since we are paying for coverage, and they should pay, but apparently they have some congress critter on payroll that permitted such a bad law to be passed. My opinion of course, and an expression of my frustration.
Mens ability to see the future is limited by their horizons of today!