Please do not take this as advise, but it is what I have experienced:
Smaller local CAs do not report accurate status to CRAs, especially in the medical area. Disputing the entire paid debt as incorrect with the CRA online can be succesful because the CA will not validate it at all. In fact, if you call the CA, thjey may very well say on their vocie response unit "if you have a paid collection showing as unpaid on your credit report, please dispute it with the collection agency directly."
Again, this is not advise, just experience.