I put €10 on my Apple ID in the App Store and I do not see the balance reflecting

Read this article about how to check your Apple ID balance.--> Check your Apple Account balance - Apple Support

- If you think that your Apple ID balance is incorrect, sign out of the App Store or iTunes Store, then sign back in and check the balance again. If you still think that the balance is incorrect, check your purchase history to see if a subscription renewed or you bought an item that used the funds. Read this support article for directions about how to see your purchase history in the App Store or iTunes Store [mobile device, computer, or web] --> View your purchase history for the App Store and other Apple media services - Apple Support

If you still have problems:

Click here --> Choose your country or region - Official Apple Support Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world."

Click here --> Contact Apple for support and service - Apple Support

*Also noted by Apple Community Specialist destiny241 in this post money not showing in my apple id - Apple Community

There where? Where are you looking for it?

How did you pay for the credit exactly? What did you do?

Have you checked your Apple Account balance?

click here ➜ Check your Apple Account balance - Apple Support