Apple Music subscription expired and I am charged, I want a refund

Perhaps this article will help:

Request a refund for apps or content that you bought from Apple - Apple Support

When did you cancel your subscritpion?

As with most things if you let the subscription run out it will automatically renew. Mine does every month (I pay mine monthly)

You should get into contact with Apple customer services and have your account details at hand to help rectify the issue.

Hope this helps