This is a sticky situation. In most cases you can't bill Medicaid patients. In this case, I would send the patient a statement and indicate that BC will not make payment until they call and straighten out the UHC thing. You technically aren't billing the patient, you are advising them they need to contact BC in order for payment to be made. But maybe the reality of getting that request on a patient statement will 'jar' them into contacting BC.
Good luck!
Michele