Cerberus Network Code Missing

I just recently bought Mass Effect 2 via Playstation store online and now I'm having problem with the cerberus pack DLC. The game is asking for the redemption code or cerberus code but I didn't receive any. I've already checked my email (purchase confirmation email) but still couldn't find it. After searching the net, I found out that a lot of people who bought their copies online are having the same problem - missing redemption code for the Cerberus DLC. Who should we contact for this problem?