Re: "Refund was rejected without a reason provided. Payment was done for subscription"
We are all Apple users, like yourself in the community, so no-one here has access to your accounts or details to check this rejected refund request out for you.
Else: The subscription may need to be cancelled first, if not done.
If you want to cancel a subscription from Apple - Apple Support
Seems if the subscription's developer or distributor has your money, Apple would not have it refund
Eg: ... payments for purchases of products not produced by Apple may be passed on for you, much as a bank or card-provider does.
✽ The best source of help for a product not made by Apple (a third-party product)
is the company or person who made it—its vendor or developer:
See how to: Contact a third-party vendor - Apple Support
or
How to contact an app developer - Apple Support
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Re: the service was not delivered.
✽ If you want, you can: Find the URL for content to report a concern - Apple Support
and
✽ You can report a problem https://reportaproblem.apple.com/?s=6
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Re: Not possible to contact with Apple.
✽ You can reach out to the Billing Support Team
Eg: (online chat / phone / email etc.) from the "Get support - start now:" link at the ottom of their website:.:
Billing and Subscriptions Support website: Subscriptions and Billing - Official Apple Support
✽ Apple support around the world : Contact Apple Support - Apple Support