You can do it yourself. I went from 500s to 700s in the last 12 months getting told things can't be removed over and over. It just takes time, persistance, and patience. It won't change over night and you may get tired and frustrated but gradually it will start working and it will pay off. It's easier said than done but trust me...it works.
What specifically did you do to get the stubborn ones removed? I have a medical one that won't give up, no mater what I do it seems, and they have a policy against PFD.
Good news with medicals there is one final ace in the hole if the others dont pan out
For unpaid medical debt that is reporting on your CR:
1. Call the OC and see if insurance can be billed, if not then 2. see if you qualify for Charity Care, if not then 3. ask that they recall the collection in exchange for full payment 4. Send the reporting CA a PFD offer 5. Google the HIPAA Process and contact its creator for help