Well, they could try and do a NAD but, despite eBay policies, blah, blah, if it's a new (or even 2nd hand item) under Aust Consumer Law (which eBay state is their default position) in a case like that it is up to the Buyer to ask questions prior to purchasing.  Actually no different than going into a real shop, spotting an item, buying it, taking it home and then complaining that it won't pick up pet hair.  If it didn't say it would on the in store advertising, packaging and you didn't ask the store staff if it would, tough for you.