iPhone storage purchase

1.

If your payment method is declined in the App Store or iTunes Store

If your payment method is declined in the App Store or iTunes Store - Apple Support

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Get more help

• If you disputed a charge from the App Store or iTunes Store, contact your financial institution again to authorize that charge and future purchases from the App Store or iTunes Store.
• If you're outside of the United States, you might need to contact your financial institution to allow international purchases.
• 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.
• If you still need help, contact Apple Support.

2.

How do I buy storage

After your payment method is not more declined, you can upgrade iCloud storage.

If you turn On iCloud you get 5 GB iCloud free storage.

When you need more iCloud storage and upgrade.

See the following Apple articles:

What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

Upgrade to iCloud+

Upgrade to iCloud+ - Apple Support

iCloud+ plans and pricing

iCloud+ plans and pricing - Apple Support

If you have an iCloud subscription, you will receive a monthly bill from Apple, check your email box.

You pay monthly for iCloud storage.

If you have upgraded iCloud storage, it would take about 1 to 3 business days in order to process.

Once your request for iCloud+ has been activated, you should receive an invoice in your email box.

See -> How to use iCloud on iPhone

How to use iCloud on iPhone – Apple Support (UK)