[The Sims 2] Sims 2 Fun With Pets

This isn't really an idea - more like a problem with no where for me to put it. 

I have just downloaded the Sims 2 Fun With Pets expansion pack and it is not installing onto my computer. I have origin installed and it does say that the game in installed - whenever I go into the Sims 2 it doesn't seem to be registering that an expansion pack has been installed. I've also tried installing the Sims 2 Pets patch - but when I go through the installation stages it just says that the Sims 2 pets isn't installed on the system and consequently shuts down. Its really starting to annoy me. 

I wondered if anybody knew how to fix or has had a similar problem? I brought the game as a digital download in the hope to play it this evening - I guess that has now gone out the window.

Any help would be great - Thank you