How to fix a payment not completed

Hello niau,

Let's start off by checking the helpful steps in this article that was linked to your posting which can help with this issue: If your payment method is declined in the App Store or iTunes Store. Follow this guidance:

"How to complete your purchase if a payment failed or was declined

1. On your iPhone or iPad, open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping.
4. Add a different payment method and remove the old one. 
5. Try to complete your purchase.

If you still can't make a purchase

• You might have an unpaid order. Learn how to pay an unpaid order.
• Contact your financial institution. 
• You might need to ask your financial institution to allow international purchases on your debit or credit card.
• If you want to know why a debit card, credit card, or other payment method was declined, speak with your financial institution. Apple doesn't have information about why the payment method was declined.
• In some countries and regions, your payment method might be declined because of changes to local law. Learn about billing and purchases in Europe or what to do if your card is declined in India.
• Still need help? Contact Apple Support."

Let us know if we can help with anything else at all or if this doesn't settle your issue so we can look into this further with you. Thanks and have a fabulous day!