Installation Problems EXTREMELY FRUSTRATED!!!!

I downloaded an expansion pack for the Sims 3, It the Ambition expansion. I downloaded the game and initially was told I need to uninstall my original Sims 3 game and reinstall it through Origin, and I did that. Then I tried to install it again and received another message saying I needed to use the Sims game launcher and update the game. And I did that, tried again and got the same message, This is has now been going on for about an hour. I am beyond annoyed and frustrated!!!!!!! I haven't been able to find a number to speak with someone. I have looked on Google as well as forms. I do not want to download or undownload another thing!!!! This is RIDICULOUS!!!!