@gusdrach, to cancel the subscription, you have to go to a platform you are originally subscribed to since Google Play and the App Store have their own administration to which we don’t have access to. The same goes for refunds.
If you are subscribed via the website (FastSpring), let me know what email address you used so I can refund you.
Here are links that will help you refund and cancel the subscription:
REFUND
App Store – https://support.apple.com/en-us/HT204084
Google Play – https://support.google.com/googleplaymusic/answer/2479637?hl=en
CANCELLATION
App Store – https://support.apple.com/en-us/HT202039
Google Play – https://support.google.com/googleplay/answer/7018481?co=GENIE.Platform%3DAndroid&hl=en