So I accidentally purchased DLC for the game "Hustle Kings" but I bought the PS Vita DLC and I have the PS3 version ! What can I do to get my account credited !
Not very much I'm afraid.
All sales from the PlayStation Store are considered by Sony as final & generally no refunds are given.
You could try contacting customer support to see if you get a sympathetic person on the other end, but even if you do don't hold your breath on the refund.