I received a message this morning saying an unknown device downloaded an app which costs $19.99. defending crowns or something like that, and the message says that if it wasn't me, I should click a link, I did, and now it's asking me to verify my credit card information and once that is done, I will receive a full refund. Sound suspicious to me, and I didn't think I had a credit card linked to my iTunes account as I always purchase gift cards instead. How can I check if my account has a credit card linked to it?
The email is spam.
You can check if you have a credit card linked by opening iTunes and going to iTunes Store → Account (right sidebar), authenticating and looking at the payment method section.