They charged me $12,574.99 for my daughter's 9 hou...

They charged me $12,574.99 for my daughter's 9 hour emergency room visit. They didn't administer any drugs and she basically slept while being on vital monitoring then cleared to go home.
My insurance paid most of the fees and I paid the balance and received a confirmation paid in full.
A month later received another bill stating I owe another $183.93.
What a scam! Overcharging then billing even more.