Health provider not responding to insurance RE incorrect coding

Essentially I went for a normal check-up and have been billed $360-something for diagnostic things, when I specifically asked *at the time* if some parts of it were included in the annual check-up (because I was concerned about the money and I’ve never had an annual check-up before) and was told yes, don’t worry.

Like, in my view I was explicit that I did not want extra things, that I only wanted the check-up which is free, and I was told it was fine and would be included, but that’s apparently *not* the case.

I called my insurance company to explain and the guy was really good, called them, they said they would review it and call back, and they never did. It’s been 2 weeks. He’s been chasing them, leaving messages, they have not gotten back. *I’ve* been chasing *him*, and in the meantime I am getting repeat messages from the health provider that I owe this money.

If the billing department won’t speak to my insurance to resolve this what on earth am I meant to do?