I've heard of freespirit and that clause. Freespirit itself is a pretty reputable organization in terms of getting work as far as I am aware. That clause is pretty dodgy though. If that's how they are planning to claim back all your tax, then why not fill in the papers yourself and tick that box yourself In reality that clause has been contested a few times already by the tax office and there's several court cases going on/been on because companies use it to claim back taxes for backpackers who according to the tax office don't actually apply for it. This has been going on for about 5 years now, so if it's still happening, nothing must ever have been really finalized on it, but if it ever is and the ruling goes the way of the tax office, it's not unimaginable that thousands of claims will be reversed and the paid out money requested back... (from the travellers themselves as they are ultimately the liable ones).
A 12.5% commission sounds absurd for what in reality is ticking one box on a piece of paper submitted to the tax office at the end of the year... just my 2p