T.F.
You don't have to have a realtor or pay someone to help you do this. A lot of scammers are out there to "assist" you for a fee. You can do this yourself and for free with little time and effort.
Make the phone call and protest over the phone. 9K higher is not that bad and they might change it for you without you doing anything but a phone call. I made the phone call and mine was dropped about $14K.
You can still get data yourself and present it if needed. Just a little leg work and you can do it with no fees.
TF