Always set up arrangements with the Hospital or original creditor, not the collection company. Once you set up the payment plan with the original creditor, you send a letter to them informing them of your HIPAA rights, namely that they cannot legally share information about your medical history to third a third party without your explicit written consent. This will remove any collection status from your credit bureau almost immediately.
Use the following links to help you get this done. I would do this on your own. There is plenty of information on the internet about how to go about doing this rather than paying some third party do take your money and do a half assed job...
Agreement to compromise debt
HIPAA letter