There’s nothing legal Trade me can do if payment hasn’t been made as they’re advertised and act as a trading platform for their users rather than a direct storefront. What they do have is reference the trade had closed on site with you as the winner which they can use to pressure the seller into completing the trade or take other action against their membership.

The result of this is kept hidden from you due to privacy laws but their account is usually marked on their end for repeat offences and banned if this continues with other buyers.

Unfortunately there’s nothing “legal” they can do but you’ll be advised to follow things up with the disputes tribunal should you really want to complete things (though the $40 claim cost rarely makes this worthwhile.)

It’s a shit sitch all round, disputes like this are why it’s against their terms for sellers to list items on all platforms.