I actually work in hospital billing and have been working in healthcare insurance and billing for 15+ years.
When you see a doctor that is a hospital based physician, there are 2 claims that go out. 1 for the individual doctors expenses and 2 for the use of the facility, facility fee or clinic charge. These charges are out patient facility/clinic charges. Depending on what type of visit the facility claim may also include labs, radiology charges, medications, vaccines etc. The payments on these claims do not go towards service for other patients. The facility claim is billing for use of the facility, nursing staff and supplies that are not included in the individual doctors bill.
What you are billed depends on 2 things, 1 what the providers contract is with your insurance and 2 how you insurance benefits process the claim. Most likely this is not a coding issue and has nothing to do with the codes that are submitted to the insurance.
If you call the billing department they should be able to have the codes reviewed for you, but codes can not be changed on the basis of getting a claim paid. The codes submitted have to match what is in your medical records and the services performed.
Insurance companies ALWAYS tell the patient that it's a coding issue, when it seldom is.
What you need to do is get copies of the explanation of benefits from your insurance company for both the physician claim and the facility claim and verify how they processed. Make sure no charges were denied because your provider can only charge you for what shows as patient liability if they are a contracted provider (in network with your insurance.)
After reviewing your EOB if you don't see any problems and they are billing you your patient liability, call the billing office and see if the coding can be reviewed.
The problem is that if they are billing correctly, and you have a patient liability for the services there is nothing you can do except set a payment plan with your doctors billing office.
Feel free to send me a message if you need additional assistance.
One additional things. Regarding your sons therapist, I would suggest to find out why your insurance is not paying. If the therapist is contracted with your insurance they should not be dropping you as a patient, they should be following up with your insurance. You should file a complaint with your insurance and find a different therapist. If you need assistance with those claims let me know. I get insurances to pay claims for a living!