Loss of a Sims code (Barnacle Bay) and elimination from the Sims Store

@ninjaferi  Barnacle Bay doesn't show as purchased in Origin, nor do any other store worlds, so that part is normal.  And once you register the product code for a world, you should be able to download it from the store as many times as you want.  The code itself can't be reused though.

Have you gone through your Store purchase history to see whether Barnacle Bay is listed?  Click Store > My Store Account > Purchase History, wait for it to load (it may take a few refreshes), and go through the pages and pages of items.  If you do find Barnacle Bay, you should be able to download it from there.

If that doesn't work, you'll need to go back to EA customer support, unfortunately.  The screenshots you attached to your post here may help, especially if you can find someone who understands how the store works.  (As in, content from the store is only available through the store, not Origin.)  An email confirmation for the registration, if you still have it somewhere, could be useful too; just take a screenshot and upload it when you submit the support request.

It may also help if you can find a record of registering the world in your ea.com purchase history.  Sign in, click your icon in the upper right corner and select Account Settings, click Order History, and set the time frame to "all."  You may need to go back pretty far to find Barnacle Bay, but if you have an order number, that may make it easier for a support rep to fix the issue, or perhaps just add the world back to your account.