Getting a human to help is impossible at Facebook, and it's on purpose. I lost $200 to a scammer on Marketplace, and the only recourse was to go through my credit card company.
... Don't buy things on Marketplace that offer shipping. The seller will give you a real tracking number to an unrelated package with the same zip code destination, which means it is much harder to claim that the package never arrived to you.
... Don't buy things on Marketplace that offer shipping. The seller will give you a real tracking number to an unrelated package with the same zip code destination, which means it is much harder to claim that the package never arrived to you.