How to report a seller?

Very "POOR" customer service. liar, nasty texts sent to buyer, rolling back of odometers, vehicle not in condition as described, told person with broken back and ribs, who drove 4 1/2 hrs. 1 way to look at vehicle, that it was in great condition, and vehicle was in poor condition. (Blowing all over inside engine compartment, tires more than 50% gone, rust all over, moldings falling off, etc.) Very poor description of vehicle, per phone/text conversations, pictures, and actual sight of vehicle. VERY UNSATISFIED, and want buyers to" BEWARE," of this seller!!!