i have big problem

You may need to have a valid payment method on file, even if the app you want to download is free.

 If you get a message -> Your purchase could not be completed, you need to Add a payment method to your Apple ID – Apple Support (UK)

• If you want to change your card, add first the new card, then remove the old one.
• or if you use your Apple Account balance, you need to set your Apple Account balance as your default payment.

See also ⤵️

Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

Add money to your Apple Account balance

Add money to your Apple Account balance - Apple Support

App Store & iTunes gift card -> Apple Gift Card - Apple (UK)

• Add money to your Apple Account balance anytime, no gift card needed.

If you update your payment method or add funds to your Apple Account balance, It would take about 1 to 3 business days in order to process.

If you're still unable to update your payment method, Contact Apple Support.

A likely reason for seeing this message is Apple cannot find a functioning payment method to use in making this purchase. You may not have the kind required or there may be problems with the ones you do have.

Use the document Add a payment method to your Apple ID - Apple Support to review your payment methods such as credit or debit cards. Problem methods will usually have a notice in red lettering below them. The article If your payment method is declined in the App Store or iTunes Store - Apple Support has some information about declined payment methods.

If using Apple Account balance to pay for an item, ensure there is adequate balance to pay for the item, including tax if applicable. Read this article about how to check your Apple ID balance.--> Check your Apple Account balance - Apple Support Some purchases may require the presence of another payment method such as a credit card even if the final payment will be made by account balance.

Providing a comprehensive listing of all possible issues and their solutions would be excessive in a single reply. If the information above does not indicate the nature of the problem then you may find the fastest route to resolution would be to accept the invitation to contact Apple for assistance with this.

To contact iTunes Support, do this:

1. Click on this link --> Choose your country or region - Official Apple Support

2. Select your country

3. Select: Billing & Subscriptions

4. Select: Subscriptions & Purchases

5. Select: Update payment method

6. Select a chat session or a phone call.