how to report fraudulent seller when they pulled down the listing

How do I report potential fraud/phishing on a suspected private seller?  I was
messaging a seller through the app, they did not answer any of my questions
directly about the car but referred me to a you tube video of the place they
supposedly bought the car from.  Then when I tried to set up an appt. to see
the car, they responded they were out of the country until 9/1.  My response to
that went unread, then the listing disappeared and so did all of the messages
in the CarGuru app.  I do have the private sellers info and our conversation
thread in my email if you need that.  Anthony Telesmatic was the private seller
name.