It's pretty simple, but as far as I know it only works with the digital download version.
Log in to your Origin account and connect to the live support. Basically do something like the image below
(Not my image above, it's from reddit apparently)
When I first saw that I thought it was a joke. Then my buddy tried it out of desperation and they gave him a code (He asked if they have any discounts).
I dunno, give it a try. Not sure how long it will last.