Replying to my own post here...
I searched EVERYWHERE today for a tool to do this, Mico's, Chesters, Humes, Bunnings, Carters, even went to Supercheap Auto's. No one had anything. Last of all, I tried LG Carder and wow, they had the ultimate tool. It's called a 'Boa Contrictor Strap Wrench' and it was on Trade special for $20. This is the love daddy of plumbing tools. It undid the thread in seconds. I've added more teflon tape to the thread and tightened it back up with the strap wrench. So, the parts will be plumbed back up tonight and hopefully this time we'll be all go! Here's the Boa Contrictor tool. I bought the aluminium version on the right:
Oh, and being a 'strap', it undoes irregular shaped pipes too! Way cool.