Someone called my girlfriend and knew her name, so she's spooked.

I don't want to start a membership with Spokeo or BeenVerified or whatever people-search sites are reputable.
I'll pay 200fg if someone can do a search on the phone number and send me the personal details.
I'll send the phone number in question by pm.

This is not allowed.

If you are genuinely concerned you can contact local law enforcement.