Mercy Hospital – Do departments communicate with each other, like billing, scheduling, collecting?

I got a bill from Mercy, a small balance that ins didn't pay. It named the clinic where I had a consultation but didn't explain what the charge was for so I called and asked. When she told me what the charge was for, I told her that I did not have that procedure done at Mercy. She said she would 'send it for review' and get back to me. A month later I get a second bill saying my 'balance is now severely past due' in bold letters with a threat to turn my account over to outside collections. No mention of a review.