Beware if you are a seller due to what could be questionable practices. Catawiki takes it on its self to frustrate contracts when it so decides, even though they make it quite clear that there is no contract between anyone and Catawiki, solely between the buyer and seller. Where I come from this is at best sharp practice, if not unlawful. So I would recommend anyone who has suffered a financial loss through Catawiki seizing monies lawfully due to the seller from other sale contracts because of such contract cancellations, to report a possible theft via the Dutch police website.