DLC is not refundable.
Here's how to return a game with the Great Game Guarantee
*You may return eligible EA full game downloads (PC or Mac) and participating third party titles purchased on the EA app for Windows and Origin for Mac for a full refund. Refund requests can be made within 24 hours after you first launch the game, within fourteen days from your date of purchase, or within fourteen days from the game's release date if you pre-ordered, whichever comes first. And if you purchase a new EA game within the first 30 days of its release date and can't play it due to technical reasons within EA's control, you can request a refund within 72 hours after you first launch the game instead of 24.
https://www.ea.com/great-game-guarantee
