I bought a number of lots of vintage wine on Catawiki. Sometimes it went smoothly, but there are sellers who will not send you the lot you won if they're not happy with the price. Instead of severely penalising such dishonest behaviour, Catawiki just offers you a refund. One seller openly told me he doesn't care about being banned because he brings Catawiki profit and they make money off him. He had 4-5 negative reviews from buyers who never got the lots they won at auctions, but he just keeps selling like nothing happened. A dismal and short-sighted business model, not recommended.