Regarding your code Issue, we advise for you to kindly submit to us a screen shot of the following in order for us to get this issue reported to the CDKey management so that they can investigate this issue with the publishers of the code as we have no direct access to the publisher's systems.
Screen shot from the Offgamers order history page showing the CD Key
2. Screenshot of the error you received on your account during redemption
Kindly send the screenshot to our support email: email@example.com.
In regards to your code issue, we have created a new ticket (#146335) for you. In order for us to assist you, please submit the required screenshot so that we could escalate your issue to the respective department. We will close this thread and any further update, please refer to ticket #146335.