3 Items: Extra 15%
4 Items: Extra 20%
5 or more items: 25%
Stack with your EB World Level.
UPDATE:
Level V will have the double extra bonus.
I.e: 5 Items 50% extra
4 Items: 40% extra.
Check your email inbox.
Also: they are accepting PS4 and Xbox one again.
you can only trade in to buy right? can't get store credit for later?