Sims4 product Key

I bought the game last night and it was installed the minuted I got it home, my little brother played it on his computer profile (its a family computer) and it was fine. He's switched everything off and gone to bed and when Ive come down this morning to play it, there's no shortcut on the desktop (the game should have been installed onto every profile). The game didn't load in intsallations manager, I've gone to Computer and it's there, I've clicked on it expecting it to open and it opened as if it was a file with Sims4autorun that when clicked on it just a picture, Origin Setup and Origin Autorun.

I clicked on Origin setup and it made me log in (Obviously) then told me to enter The Sims4 product key which I did and is now saying the key has been used. 

This game should already be installed but it's disappeared. 

I would like this sorting cause this WAS NOT a cheap game at £40 and now I can't even play it. I'm feeling really rather ripped off.