PS UK CS here. We've no idea what caused it, anything else is speculation.
Hundreds of people in a queue on call, but amazingly, everyone is incredibly understanding. Not a single person going off their nut at us, at least not in my experience. Not even asking for compensation.
And to that one person saying that we don't refund digital pre-orders, you're dumb. Call up support. We do. You just need to not have accessed anything relating to it, such as a free pre-order theme or avatar. And its a card refund, not a wallet refund.
BAH GAWD people are so misinformed about how PS Support works.