Totally agree but to my thinking if I go to a DME that my insurance recommends they damn well should at least make an attempt to answer my questions (which I would then of course verify with the insurance company) and make a damn phone call if they can't answer the question.
If they aren't willing to make a simple phone call....pretty sorry DME and like I said...run don't walk away from that sort of service.
There's someone in their billing department whose job it is to figure this stuff out....and if there isn't...another reason to go elsewhere.
I would also report to the insurance company the level of non service I got from someone they recommended I go to and maybe they should reconsider recommending them.
When I get on my high horse for the principal of the thing I can ride it a long way.

I can understand not knowing....but what is unforgivable to me is lack of trying to find out whatever it is they don't know.
Obviously a don't give a crap mentality there....would make me wonder what else they don't give a crap about.
I wouldn't buy so much as a filter from a place like that.