I have also had the problem since Sunday when I purchased Sims 4 Seasons. It wouldn't download and then when I spoke with a EA support person, they told me to uninstall and install origin. After doing so, I lost all of my games from my Game Library and have the "servers temporarily unavailable" message.
First I had problems with updating my game because it couldnt verify the game files so i deleted origin like the tech said and now ive been having this problem... ugh
I just got off with the phone with EA they are aware of this issue and said origin caused an error basically when they did an update for the mac and this game meaning huge errors, he said they've had a lot of calls for it obviously and its been going on for a week! (A BLOODY WEEK!!!!) he apologised and said all we can do is sit tight and wait, he also said hopefully they'll get around to fixing it and creating a patch soon.
We seem to be small fry to origin!! absolutely fuming, nice to know they give a Sh*t about the customers and the amount of money we've put and keep continuing to put their way.