Refund on my wordpress payment

I have had my domain since May of 2014 and unfortunately did nothing with it. I got a notice while I was out of the city on April 29 2015. I noticed the e-mail late. It said that my domain will be expiring on May 29, 2015. However, I received my credit card statement and noticed that wordpress had already charged the annual payment. Does this mean that if I cancel my domain before May 29 or up until 2 days after the expiry of my account, I will get a refund? How does this work? I would have thought that they would charge the fee as of the expiry date. I don’t know anything about wordpress, bought the domain on a whim, and now I’m paying for a second year ?? which I hope I can reverse somehow… with your help!
Thank you.