How do I request a refund for the money that was deducted through Autopay ?

Do you have any subscriptions?

View or cancel app subscriptions on iPhone - Apple Support

You can try requesting a refund, but any subscription service you sign up for is a agreement that you have made to pay for the service.

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

You don't get a refund for any unused portion of your subscription and you can continue to use the service until the subscription period ends. Since you have cancelled the subscription, it will no longer renew.