What can you do when you've been paying medical bills but the hospital reported it to the credit bureau anyway?

First of all if you did not start paying on the medical bills until they were in collection, then they were going to be reported anyway. Although you are currently making payments on an account there are still limitations to how long you can take to make full payment such as 30, 60, 90, and 120 days. Unless specified or if you have made arrangements with the creditor then after 120 days legally they can sue you for the remaining balance. The key to not having it reported is to set up a payment arrangement. The only stipulation to this is if you miss one payment your account can immediately be stne to collections. This is not legal advice. If there is more information not disclosed in the above question, please contact creditor, credit bureau, and a lawyer.