Cannot purchase from the PSN App or website

When I go to the App on iPhone or the PSN store in a browser I cannot purchase games.

I successfully purchased PSN+ today but I am trying to buy a game and it won't let me.

I go to the cart, hit "confirm purchase" and it tells me the following

"Your purchase may not be complete, check your transaction history"

Can anyone help? I'm on PSN Australia for what it's worth.