Product: Debt collection

I had a scheduled checkup last year ( XX/XX/XXXX ) at her XXXX for which I had to be put under general anesthesia during the checkup. We had scheduled this appointment after assurance by the doctor 's office [ which is in network of our health insurance provider ] that everyone involved in the checkup procedure will be billed as in-network. We were given the name of the XXXX who gave general anesthesia to me on day of the appointment, Anyway the check up went fine and waited for the explanation of benefits ( EOB ) from the health insurance and bill from the providers to pay for what were expected to be in network charges. 
Sometime mid-year ( XX/XX/XXXX ), we ( me and my spouse ) got an EOB letter from the health insurance saying that the charges from the XXXX will be calculated as out of network since the XXXX is out of network. This was the first time we even came to know the name of the XXXX. Facing a bill of around {$3000.00}, we called the XXXX office and asked them why they did not inform us prior to the procedure that they were out of network of my health insurance.They told that they were working with the health insurance to claim the bill as in network since the procedure was performed at a doctor 's office location that was in-network. 
Since the health insurance did not pay to the XXXX office for the claim that the XXXX office sent them, the XXXX office sent us a bill last month ( XX/XX/XXXX ) with adjustments and asked us to pay around {$500.00} to settle the bill after adjustments. We asked them to provide me breakdown of how they calculated the {$3000.00} bill and when they sent me the details, we was astonished that billed me incorrectly stating the time for the procedure was 87 minutes, even though we clearly remember is being under 30 minutes. When we asked them on the phone about why they mischarged the bill, the XXXX spoke very rudely with us said that they were not going to discuss any further details and threatened us to either pay up the {$450.00} ( since we had paid {$50.00} on the day of the procedure itself to the XXXX office ) or they would send my bill to a collection agency. We asked them to work with us and correct the bill for the service they provided but they just hung on us and stopped responding to our phone call. 
Recently we got a chance to speak with them again on the phone and they told us that my bill was handled by a different office and gave me a XXXX number to call. When we called the provided number, the person responding to the call mentioned that they are a collection agency. Now we believe that my rights as a consumer have been violated since there were mistakes done by the XXXX office at multiple levels which I have listed below : 1 & gt ; Since the checkup as a scheduled checkup, the XXXX office should have informed us that they are going to charge me as a out-of-network service which they did not do. 
2 & gt ; I believe that they billed me incorrectly stating the time for the procedure was 87 minutes, even though this was a simple procedure which definitely did not last 87 minutes. 
3 & gt ; When we was trying to work with the XXXX office after receiving their bill with adjustments to pay {$450.00}, I was trying to figure out how they arrived at the original {$3000.00} bill that they claimed, but they refused to provide me any further information and sent the bill to a collections agency to make it impossible and inconvenient for us to challenge or question the bill they they charged. I believe is again a violation of my rights as a consumer of health services and the XXXX office did not handle my account properly as required by law.