I want to cancel a subscription

When you cancel a subscription, the auto-renew is turned off, and the access to the subscription service lasts for the complete current billing period, until the expiration date. I.e. cancelation does not end the service immediately.

You can’t cancel for dates the past, only for the next billing period.

You should cancel a subscription at least 24 hours before the renewal date.

In general, there are no refunds (“all transactions are final”), unless errors were made.

You may contact iTunes Support Accounting by filling out the form:
www.apple.com/emea/support/itunes/contact.html

Then you have to cancel the subscription yourself AND convince the iTunes staff, by filling out a form, explaining the situation and making your request.