Please try this website instead of the Origin client: https://account.origin.com/cp-ui/redemption/index
If that still doesn't work for you, please contact a Game Advisor at https://help.ea.com/contact-us who will be able to assist you with this.
1 Click on the following link: https://help.ea.com/contact-us
2 Click on the blue button "Contact a Game Advisor"
3 Enter the name of your game or product (or "Origin" for account-related issues) and click "Find Solutions"
4 Select the type of issue and the platform you play on, and click on "Find Solutions" again.
5 Click on the blue button "I still need help" if the FAQ articles do not apply to your situation.
6 Select a contact option. Note that you may get different contact options depending on your country or time of day.