Subscription

Basically, your membership or subscription might renew if you don't cancel your membership or subscription more than 24 hours before your renewal date.

In case if you need information about refund possibility: Request a refund for apps or content that you bought from Apple - Apple Support

If necessary, contact iTunes Support. Either use the form or scroll to the bottom of the page in the 2nd link. Follow through the screens to get a chat or telephone option.  

iTunes Support

iTunes Support – world wide