How do you get your money back from a purchased app

If you have received an invoice from Apple, on every invoice from the Apple Store and/or iTunes Store always states what you have purchased (and/or concerns a subscription) and the amount.

Tap on Report a problem on the invoice.

Or try to ->  Request a refund for apps or content that you bought from Apple.

Request a refund for apps or content you've bought from Apple – Apple Support (UK)

If you have requested a refund, you must wait until Apple has approved. Then you will receive a message from Apple.

Refunds are not guaranteed. For more information, see the Terms & Conditions.

Click ▶︎ Request a Refund.

According to Apple:

If your refund is approved, the funds are applied to the same payment method that you used to buy the item.

Here's how long it takes for a refund to appear on your account or statement:

Store credit—It might take up to 48 hours to see the refund in your Apple ID balance.

Mobile phone billing—It might take up to 60 days for the statement to show the refund. Processing time might be affected by your carrier. You can contact your carrier for an update.

All other payment methods—It might take up to 30 days for the statement to show the refund. If you don't see the refund after 30 days, contact your financial institution.

Click ▶︎ Check Refund Status.