Hello rcire.
Take a look here & see if it helps out:
Invalid and Used Serial Codes & Games not showing up in Origin
Are these 2 EPs the only TS3 Content that weren't Digital Downloads? If so, did you register them at thesims3.com website? Registering Retail DVD versions of TS3 EPs at thesims3.com is a requirement in order to get a free digital download copy. Did you use the same info (ID, E-mail, etc.) for both (Origin & TS3.com) Accounts?
Redeem Your Serial Code in Origin
1.3 Exceptions to Origin redemption: *There are a few exceptions where these steps will not work: The Sims 3 - Your code has to be redeemed on the Sims website https://www.thesims3.com/registeragame.html in order to be "registered" in Origin.
Did you ever have the DVD versions of the 2 EPs installed on this new PC? If so, you'll need to fully uninstall them, registry keys & all, before you can successfully download & install the Digital versions.
With your serial code, you are eligible for the download version of your game. You can download it through Origin and redeem your code. Instructions on how to do this can be found here: Redeem Your Serial Code in Origin Make sure to uninstall the DVD version and install the download version instead.
Source: http://answers.ea.com/t5/The-Sims-3/FAQ-Lost-and-broken-DVDs-and-missing-serial-codes-What-to-do/td-p/14230
Here's instructions on how to manually uninstall:
