I use eBay primarily to buy and very very rarely to sell, but I was editing my bag collection and put two bags up on eBay (both Diors), both with very detailed descriptions and pictures. They both sold at their BIN price. One of the buyers emailed me after having received her bag to tell me that she doesn't think the bag I sold her is authentic. I'm aware that there's a scam out that where buyers make the same complaint and will send back a fake bag. I've emailed the buyer telling her to come here or ask for authentication from a boutique. Where else can I send her for authentication? What are my options? (And just to be absolutely clear, yes, bag is 100000% authentic, but I no longer have the receipt.) TIA.