Claim denied for a 911 emergency

Our insurance (Aetna) denied the claim for our emergency call. My husband had a little black out in the kitchen. He was experiencing high stress levels due to a major life event. I called 911 and the team showed up which was also in network. His blood pressure was extremely low if I heard it correct then. They waited around, asked him a few questions which was very hard for him to answer since he was extremely disoriented and frankly a little scared since he didn’t understand why so many people were in our home (as he later recalls). They kept taking his vitals every few minutes until he stabilized. He was then moved to the hospital. Nothing came of it, he was just asked to take it easy. There was no medical explanation for why this happened. They did a bunch of tests to check for injuries on the head after fainting, ekgs and works to check for heart attack, even urine tests, drug tests etc that all came negative. Today we saw a bill reflecting on our Aetna account, saying we owe them $5200, from the said in network hospital.

If it helps, we are in the state of New Jersey, the said first responders/ambulance was from Virtua which is in network with our Aetna insurance plan.

The aetna bill says, as of now the claim is denied, but we don’t owe anything yet & they need more information from the provider. I’m panicking a little and looking for support.

Edit: Bill coded under A0427