Not sure off hand. I know you can report a transaction.
Ordered some arcade parts a few years back and the company went 1 week without shipping the order. I reported the problem to paypal (After multiple attempts to contact the seller) and I guess paypal contacted the seller who then contacted me telling me they were away at a convention and shipments were delayed. They ended up shipping the order after a few more days and it didn't go any further.
I know it doesn't mean too much on the net but I'm not trying to screw anyone out of $20 in RVN. I just don't want to sign up for some oddball exchange and plan on holding the RVN I buy.