Re: "subscription not recognized in app Apple refuses refund"
Seems Apple passed the payment to the vendor or developer for you, much as a bank would do, so Apple doesn't have your money to refund.
About purchases not billed through the App Store or the App Store’s In-App Purchase system - Apple Support
Some countries eg: India, or Europe and Japan, have particular requirements:
More info: About billing for Apple subscriptions and media products in India - Apple Support
or
About billing and purchases in Europe and Japan - Apple Support
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Re: I tried to reach the developers several times from different channels, and no response!
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 Apple support's articles below for tips:
Contact a third-party vendor - Apple Support
or
How to contact an app developer - Apple Support
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Re: I paid for annual subscription and have nothing. What should I do?
Maybe there's a website, an app, an online community of subscribers, or something similar.
Either find a way to download, make use of, or join the subscription you paid for,
View your purchase history for the App Store and other Apple media services - Apple Support
See how to: Redownload apps and games from Apple - Apple Support
and what to do:
If there’s an issue when you redownload apps, movies, or other content from Apple - Apple Support
or if you haven't already: you can cancel the paid-for subscription (ie: so you won't be charged the next year ?) What to do: If you want to cancel a subscription from Apple - Apple Support
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if you want to : You can report the issue you are having :
Eg: First: Find the URL for content to report a concern - Apple Support
and
See: How to report a problem : https://reportaproblem.apple.com/?s=6
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If needed: More info. / support / contact options etc.
Billing and Subscriptions Support website: Subscriptions and Billing - Official Apple Support