i haven't received my email for my pre-order what do I do?

I pre-ordered the 5 Seconds Of Summer Don't Stop EP and Don't Stop single yesterday and it came out today. I haven't recceived my confirmation e-mail to say is has been released and I have checked through all my e-mails at least 3 times and I can't find it. When i go onto the iTunes store and search for the items I have pre-ordered it comes up with purchased and I'm really confused what do I do because I can't buy it?