I seriously doubt you are going to a refund for the DLC. You should know that DLC is region specific of the Playstation.
― William Faulkner
I just had to buy the DLC.
But that DCL does not apply to my Playstation.
I want to receive a refund of the DLC.
I'll wait for your fast answer.
Welcome to the PlayStation Community.
I'm not really understanding your question too well, but I'm assuming, perhaps incorrectly that you have purchased some DLC from a region or country other than that of the original game?
As the other poster said DLC has to be purchased from the same country or region as the original game, please also note that the Sony PlayStation Store has a no refund policy, you could of course try contacting them (see below the "contact us" link at bottom of page) but don't hold your breath, sorry!