How to cancel a subscription on Apple Account that mistakenly renewed?

This is a user to user support forum, we can't directly help you get a refund.

You can request a refund by following the steps in this guide:

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

You are not guaranteed a refund tough.

This is an automated process, if you wish to explain your situation in-depth to a person you can:

Contact Apple for support and service - Apple Support 

Also, see this:

How long refunds from the App Store or other Apple services take - Apple Support

Good luck!

Thank you for replying with your concerns, kajan209. 😉

Here at the Apple Support Community, we are volunteers (thoughtful Apple users) who share knowledge in an effort to help others, such as yourself.

We don’t have the power to look into accounts or make changes.

Only an authorized Apple employee would have access to the resources to help you.

I wish you the best, but you must contact Apple Support for further assistance.

All the best! 👋🏼😉