View, change, or cancel your subscriptions - https://support.apple.com/HT202039 - "Learn how to view your subscriptions that renew automatically, change your subscription period, and turn off Automatic Renewal." "If you don’t cancel more than 24 hours before your renewal date, your subscription might renew."
For a refund you can try:
Report a Problem - http://reportaproblem.apple.com - "Sign In for help with iTunes purchases made in the last 90 days"
If you have unsatisfactory results with that method then:
iTunes [Store] Support - Use this form for assistance with account and billing, code redemption, or purchase questions - https://ssl.apple.com/emea/support/itunes/contact.html
Worldwide iTunes support - https://support.apple.com/country-selector/itunes