Target Team Member here...
Actually you will need to bring in the item and return it. A price adjustment by reciept only can happen in a 14 day window if it goes on "sale" (excluding clearance)
You will need to return the item, and then go out to the sales floor to purchase a new one. (So make sure it is in stock before you return it!) The team member at the service desk cannot simply resell the same item back to you.
If it has been opened, it will need to be exchanged with the new game (same title) in one transaction... copyright laws forbid the return of opened movies, music, games... but exchanges in the same title are allowed