@EggyLady You may well have been scammed, by Instant Gaming. Or rather, by whoever sold Instant Gaming the product key that it sold to you. This is the risk in buying from an unauthorized third-party seller: you can never be sure you're receiving a legitimate product.
Your only move now is to ask for your money back. In the future, if you want to avoid situations like this, it's better to buy from Origin itself, or from an authorized vendor.