Refund for an Add-On

I accidentally bought the Star Wars Celebration edition without owning the main game and I'm trying to buy the game but bought the Add-On instead. The refund process will not pop up as it states that "I do not own any game for return" Since an add-on isn't a game. What do I do in this scenario to get refund so I can buy the main version of Star Wars Battlefront 2.