Click on this link to learn how to contact an app developer to let them know you are dissatisfied. - How to contact an app developer - Apple Support
You may wish to note: "All Transactions are final."
Apple's terms of purchase in the USA are, "All Transactions are final," ( Legal - Apple Media Services - Apple section B), but check the terms for your country. Even if Apple does not outright say in a country that sales are final, they may say that refunds are only made to remedy defective or unavailable product. In other cases Apple may make limited refunds solely at their discretion and as an exception. Apple can also simply say no without having to provide a reason. I understand this can be frustrating but by using the service you agree to the terms.
Here's how to request an app or media refund from Apple (From: Request a refund for apps or content that you bought from Apple - Apple Support - see the article for more detail.) If you bought this in the EU from a third party, see: About purchases not billed through the App Store or the App Store’s In-App Purchase system - Apple Support instead.
1. Sign in to https://reportaproblem.apple.com
2. Tap or click "I'd like to," then choose "Request a refund."
3. Choose the reason why you want a refund, then choose Next.
4. Choose the app, subscription, or other item, then choose Submit.
If you were charged for a subscription that you no longer want, you can also cancel the subscription using the directions in this article --> If you want to cancel a subscription from Apple - Apple Support
Read this support article for information about how long it takes to receive a refund (if you are granted one), and how to check the status of a refund for apps or content that you bought from Apple --> Check the status of a refund for apps or content that you bought from Apple - Apple Support