Yael, not sure where you would go in Vic for it, but in NSW some mechanics are approved to do it and put the new anchors in. You could try checking with Vic roads or RTA (not sure what they are called down there). We've been lucky and our car came with two - one in the middle and one behind the front passenger. You would have to have the three in there as you wouldn't be able to attach it correctly the way you've suggested. I don't think it would cost a lot of money to have it done though - it doesn't take long.