I will assume you've followed my wicked tips for safer transactions.
Time is crucial. The slower you are to react to getting scammed the worse off you are.
If you are buying, contact the seller. By phone is preferred. Contact paypal and file a report. Contact your credit card and let them know you believe you've been scammed. They will tell you that paypal will handle it, but if paypal cannot resolve the issue your credit card company will stand up for you and investigate as well. If the seller is or becomes a known scammer, contact your local authorities and the authorities at the sellers location. If enough victims of the alleged scammer come forward file a huge case with the FBI's fraud unit (since you have all the scammers CORRECT contact info). There is currently a joint investigation between FBI and RCMP against a repeated cell phone scammer in Toronto.
If you are selling, there shouldn't be a problem because you've followed my rules right? But if something does happen, let's say the funds were paid in an illegal way (w/ stolen credit card? which you should have seen coming if you read my tips), then stop the delivery of the package. This will cost you money, but it is better than losing your gear.
DO NOT, I repeat DO NOT use vigilante justice. YA i know your pissed but do not get into legal trouble for hurting the alleged scammer. If you've followed my tips and have substantial proof of payment/shipment, and kept all records of contact between all parties, then LET THE AUTHORITIES HANDLE IT.
Let the PBF community know you've been scammed. Leave the scammer negative feedback. Contact a mod, have the scammer banned.
REMEMBER, nothing is 100%. Even if you follow my tips there is no guarantee. In fact there is never a guarantee, which is why you should DEAL LOCALLY. Otherwise, support your local PB store and buy retail.
Check this link:
http://www.trollhunters.com/ for more tips and some useful links. The more you know the better off you are.
I've been scammed before...once using Western Union, twice using paypal, once during a trade. Each one over $500 CDN worth of cell phone stuff was lost. Both paypal (i was the buyer both times) losses were recovered, Western Union (i was buyer) funds lost forever, for the trade i hunted the scammer to his home and spoke to his parents, cell phone was not recovered but got money back as compensation.
I will admit that after the bad trade, I was out looking for vigilante justice. Please keep your cool, you need to be able think clearly and quickly when you've been scammed. Do not ruin your chances of getting your money/items back or ruin the chances that the scammer will face any legal punishments.
Please learn from my errors. Do not let the same thing happen to you. I have seen this happen too many times to people that do not deserve the frustration and anger of being scammed.
If you need more help or advice or you are unsure about a deal that is about to go down, pls do not hesitate to PM/MSN/ICQ me.
Most important tip if you've been scammed: do not feel helpless, contact me.