My son had a minor in & out surgery earlier this year. Could have done it in the office, but the doctor recommended a surgical center that was out of my insuran

My son had a minor in & out surgery earlier this year. Could have done it in the office, but the doctor recommended a surgical center that was out of my insurance network. "Our patients have been very happy with the price." I called the surgical center, and was told it was a flat fee of $500, payable in advance, for which I received a receipt: "Facility fee". We did the surgery. The doctor's bill was well under a thousand dollars. Almost six months later, the surgical center sent a bill to my insurance for $48,000 as a half-dozen line items, each listed as "facility fee". My insurance says they paid $25,000 and the patient responsibility of about $10,000. We haven't seen a bill from the surgical center, and I told the insurance it was either a billing error or fraud, as it was 100x the price I was quoted and accepted up-front.