DLC Code Redemption Error

Hi everyone,

I recently purchased a sealed Dragon Age: Inquisition Prima Games strategy guide off eBay, and I've been attempting to go through the redemption process for the promo DLC (mount + ring). I was successfully able to redeem the code on Prima Games' website (which tells me that the code was valid and unused), but the code that Prima gave me to redeem on EA is not working on the EA website or in the EA App. It seems to recognize the DLC correctly when I type in the code, but every time I try to add it to my account, I get an error message saying "An error has occurred while trying to process your request. Please, try again later." I've attached a screenshot of both of these messages.

I did contact support and they were unable to resolve the issue due to the code not coming from a trusted retailer, which I cannot do anything about. However, I can prove that I own the product, both physically and digitally on Prima Games' website. I'm not sure if the issue is that the code is 10 years old and has some kind of expiration date, but there was nothing about that on the card inside the strategy guide. I did see someone had a similar issue back in 2017 (https://answers.ea.com/t5/Dragon-Age-Inquisition/Dlc-code-Recognised-but-not-working/m-p/5868853/highlight/true), so maybe there's just some problem with this promo.

If anyone knows how to help me, that would be amazing. Thanks!