I called the phone number on my bill, ( I received...

I called the phone number on my bill, ( I received it 5 months after medical services) and it said "Your call cannot be completed as dialed please hangup and try your call again or contact customer service" I tried calling several times only to receive the same message. Then I tried their number from the website and it too said the same thing. How do they expect me to inquire about my bill if they put this on their answering machine?
TERRIBLE CUSTOMER SERVICE.
TERRIBLE BILLING ETHICS.