How to cancel unwanted subscription charges on Apple Account?

Hello, I recently had a free trial of a guitar program, and I canceled it a day before it was due. Yet it had charged me for a years subscription that I do not want. I didn't pay the money for it, I didn't authorize the purchase yet it repeatedly tries to charge my card and I can't make new downloads. I do not want to pay for something I did not buy, and I canceled the purchase through apple; yet it keeps trying to charge me. How can I resolve this issue without paying the money, because $40 is ridiculous. I have been through every official apple article with the relevant issue, yet none are helpful.

[Re-Titled by Moderator]

Original Title: Pending Purchase of a subscription I canceled