If the invoice/sales docket says the item is 2nd hand then all consumer law relating to new items is rendered moot, only any laws covering sales of 2nd hand gear applies.
Euro consumer protections are very similar to Aussie ones, we have 7 days (14 in some states) to return a defective item even on 2nd hand gear - only exception is if was sold in unknown or not working condition, then it's buyer beware.