I pre-ordered a CD from iTunes and was supposed to get it today but never received it, what should I do?

I'm not sure how long it's been since I've pre-ordered this certain CD, but I'm just going to say it's been about a month. Today the CD came out, and I assumed I would get it right away automatically. I've pre-ordered other CDs before and they came through just fine without having to do anything. What should I do about the CD I haven't received yet? I still want it, but I don't want to have to revive the whole CD again since I've already spent money on the pre-ordered version...