I've been watching this thread for about a month now when the issue started for me and I'm beyond flabbergasted with how long it's taking. In my opinion, it does seem like maybe they're working on it as when I try downloading packs now, I don't get the "something went haywire" message anymore, it just doesn't download my packs, but regardless, this problem should've been fixed by now.
Not only are we having problems too, but aren't people having trouble with other games not being able to install add-ons like Battlefield and a few others? And some friends have told me that there's a really annoying bug with TS4 that's ruining their sims' relationships. All of these issues and EA is yet to fix any of it. All we've gotten is the same copy-and-pasted message and no real change has been done.
I love TS3 to death so I won't give up on this until it's fixed, but this is ridiculous and they should know by now that sitting around reluctant to fix the issue will only make us more upset.