I just thought I would post this to help other PSN users avoid the same mistake I made earlier today.
I turns out I wanted to the buy BF3 Premium Edition (i.e. the BF3 game + the premium pack) which is currently available for pre-order by another major online retailer for £39.99 (which is where I saw it first), however it isn't released until the 14/09/2012. To my suprise and joy it is available for download on the Playstation store and I saw it advertised for £39.99. So I read the decscription 'Battle 3 Premium (Game Pack)' includes expansion packs etc ..., I thought great and bought it.
In turns out I paid £39.99 for a BF3 Premium (not BF3 Premium Edition) which requires the base game (for £49.99 on the store). I am so anoyed as the product description didn't mention that the base game was not included OR that you need the original game to use the download. Now this may have seemed obvious to those who already own BF3, but with BF3 Premium Edition now being avaliable it is very easy to mix these two up. I'm now left with a £39.99 expansion pack I can't even use unless I fork out another £49.99 which I refuse to pay. It turns out the 'Premium Edition' is available on the Playstation store to for £57 (way more than £39.99 listed online elsewhere), but I have discovered this afterwards.
I have raised this issue with Playstation Support to get a refund but they are saying becauase it's not faulty (technically I have no way of knowing whether it's faulty or not) they can't refund me the money. I think this is very poor behaviour by Sony given the poor product description. I have taken pictures should this need to get legal, but the whole thing seems silly and Sony need to show some common sense given the circumstance. I have phoned them up (at 4p a minute) to complain a second and await their response.
Anyway, make sure you get the correct version according to your need as you might be suprised like I was!