NFS Most Wanted DLC not working on my ps3.

I downloaded the heroes pack and the ultimate speed pack, none of them work. I re-downloaded and re-installed the add-ons and still the problem persisted. Whenever I find one of the DLC cars on the map, I drive to it and it tells me to go to the store. This is nonsense, please EA fix this problem quickly, or give me a refund if you can't fix it. I really want the DLC cars, thanks.