To give you some hope:
We got on a new ACA plan in 2020, and got a new primary care in-network doc, who sent us to his in-network hospital for lab work. Only, that lab was out of network (Quest). So we were billed $600 each, instead of the expected $50. Later that year, the US passed an anti-surprise biling law, but Texas has had one since 2016. I called the insurance company to complain about it, and they did fix it. It took 3 months, and the call took some time to explain, but there wasn't a wall of denial / inaction / other wrong action.
Long ago, we also had a doctor's office that sent us a bill, because they had tried to bill my wife to Medicare. We are not Medicare participants, and this was not our first visit there. They are in a different state, but were in-network. Reversing their error involved 3 BCBS affiliates: the one in their state, the one in our state, and the one in the state of my company's headquarters, who administered their healthcare plans. There was more than one call that said: "Yes, I can see the error. But I don't have the access to change it." Took several phone calls, but nobody was antagonistic, and it got resolved.
We still get explanations of benefits for the insurance company we left in 2022, adjusting and discussing visits for my son in 2021. It's never our concern, and I'm sure it's automated. But the system is complicated, even without a customer's input!