I had a wild experience with an eBay win. I won a LV speedy auction about 10 years ago. The price was the going rate for a second hand speedy at this time.
When it arrived, it was a clear fake. I was so disappointed. I contacted the seller, who denied it being inauthentic. I did a side by side with my friend's (bought new from LV) and sent the seller a bulletpoint list of the markers for it being a fake. I was apologetic and polite (she may not have known it was a fake, after all), and she went totally silent on me. For weeks.
I can't exactly remember the back and forth with eBay and PayPal, but after the seller ceased communication, and eBay said they couldn't help me, I decided to take things into my own hands.
I couldn't take it to LV as they would have seized and destroyed it and I'd lose my evidence (or so I feared).
So I turned detective.
The eBay account gave no contact details... so I turned to PayPal.
The PayPal account carried the email address of a man. First name last name and a number indicating his probably DOB. This guy had another item listed for collection from a particular area of the UK. The seller I had dealt with was definitely a female and had signed her first name on one of the two emails.
I ran the PayPal email through Facebook and found the man using the probably location and his probably age. I looked through his fb friend list and discovered one person of that name. I finally had her full name. I googled her name and the location from eBay and found her on LinkedIn.
After sending her multiple messages on eBay over the next few weeks and getting silence, I decided that I didn't want to lose hundreds of pounds on a fake handbag. I sent a polite email to her work email address expressing my disappointment with the fake handbag and requesting a full refund.
She then finally got back to me and gave me an address to post the bag back to, apologised for it not being genuine (she claimed that she had't known...) and gave me a full refund.
If I'd have had mumsnet at the time, it would have been an edge of your seat, live update event. My friends were thrilled with the drama of it all.
You'll either decide that I am a tenacious and resourceful person, or an astonishing psycho from that story!