Yea, I had tried it that way and by just searching for the game (and later the actual dlc pack). I tried again just now doing it your way but it's still a no go, collection 2 still isn't listed, the only add-ons that are listed listed on the MW3 page for me are Collection 1, Collection 3, Collection 4, and two free packs. And again if I search for "collection 2" and pick the page for it out of the results it just says "Not available for purchase". But if it works for you then it can't be a regional thing, which is what I first thought.

I did figure that might be the case these days, however I tend to play CoD a lot mostly offline splitscreen with my mates, plus I like doing the Special Ops missions so it probably won't matter too much to me if I can't get any games out of it online. I only ever bothered to pristege once online anyway.