After the false start previously, the network and amaysim have worked hard on creating a cashback model that works for them, it is a little bit more complicated, see the Additional information section on the amaysim MBC offer page.
Basically, if you sign-up for amaysim through Moneybackco you can get up to $25 cashback on a pre-paid purchase and $30 cashback on a post-paid purchase.
Thanks, Steve.