Hi,
I see three posibilities for what happened here :
1. It is a phishing email.
2. Someone else shares your Apple ID and didn't tell you they renamed their iPhone or switched to a new one.
3. Your Apple ID is compromised.
You can sign in at Report a Problem or use iTunes on a Mac or PC (see See your purchase history in the iTunes Store on a Mac or PC - Apple Support) and see the latest purchases made from your account. If you see anything that should not be there, contact Apple directly. On the Report a Problem webpage, there is a button next to each purchase made within the last 90 days which allows you to, well, report a problem.
If you don't see any purchase that would explain the charge you saw on the invoice, maybe the invoice is fake. Here is Apple's advice about phishing emails :
Identifying legitimate emails from the iTunes Store - Apple Support
Identifying fraudulent "phishing" email - Apple Support
http://www.apple.com/legal/more-resources/phishing/