Let me guess... The Nigerian buyer was buying a laptop? For your
FVF you can file a NPB alert and get your
FVF back (in "my ebay" on the left-hand column).
Hey, I am really sorry to hear about your issue with PreyPal. They are really uncool about these types of things. Seizing your money after you shipped a product. That is so wrong. But that is one of the down sides of having a merchant account (yes using PreyPal is like having a merchant account).
I have had many transactions go into A) dispute B) temporarily withholding by paypal. I actually have one dispute open now. She says she never got the package. And it's sitting at her post office (with del con). She doesnt return phone calls and my email bounces back every time. Then she files on claim on me? Anyway, that is no big deal. You know why I am not worried about it? There is one simple way to AVOID ALL OF THIS!
ARE YOU READY FOR IT?
Here it is (two parts):
DO NOT SHIP ANY ITEM TO ANYONE UNLESS IT IS A CONFIRMED ADDRESS. Make it your policy and stick to it. Make sure all your shipments are eligible for "paypal seller protection." The second part to this, and it is a MUST, you MUST HAVE PROOF OF DELIVERY to the buyers CONFIRMED ADDRESS (UPS offers for free, USPS is .45 or .55 depending). I ship all my stuff thru Paypal's shipping feature and its free (the little link that says "ship" in your transaction details). That way paypal will always have the proof they need right on their system.
Unfortunately not many international addresses can be confirmed. Canada can be and so can UK (but most aren't). Australian is not able to confirm. So it is up to you if you want to risk it with non-confirmed international buyers. Most of my business is USA, UK, Canada and Australia. I chance it with Australia.
You can also go into your paypal account and select different payment options... I choose not to accept echecks, bank account transfers when a c.card is on file and block all payments from NON CONFIRMED ADDRESSES.
Some buyers will try to get you to ship to a different address than what is on the account (they add it to the note section). When this happens I email the buyer and let them know my policy and mention that Paypal has suggested this policy for me... "bla bla bal ... it is for my protection as well as yours... bla bla bla" Most buyers are cool with it. And if they aren't... well... chances are? Then I tell them to confirm the address they want it shipped to and resubmit payment (I refund original payment), or I will ship to the address on file.
Knock on wood, I have won every dispute/withholding to date. I got lucky a few times before I learned about the paypal policies.
Sorry for the short book here

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Good luck to you. Let us know how it turns out.