Have you experienced an error while purchasing with Apple App Store?

Pending purchases usually gets cancelled in time.

But if you had been charged, please request a refund.

Go to settings on your iOS device.

Open the Settings app.

Tap your name, then tap Media & Purchases. 

Tap View Account. You might be asked to sign in.

Tap Purchase History.

iPhone showing the Purchase History menu option in Settings.

Your purchase history appears. Tap Last 90 Days, then select a different date range.

Find the payment in question and ask for a refund.