I remember some years ago when I had surgery, the surgery was pre-authorized. After the surgery I received a bill for $20k. Insurance refused to pay the surgery

I remember some years ago when I had surgery, the surgery was pre-authorized. After the surgery I received a bill for $20k. Insurance refused to pay the surgery place and eventually both parties settled it. I ended up speaking to someone at the insurance company that I went to school with. She said that for this procedure and amount of time for operating room the max they pay is $2k. So, there was no way that company would see $20k. I also refused to pay as patient is responsible. Few years later I received a proper bill for $300. It was long after they could collect, so I told them to beat it.