Why can’t I update my payment method on my iPhone?

No, you did NOT explain that the instructions did not help, you didn’t even say you tried the instructions or which instructions you tried. But perhaps this can help:

A “payment declined” or “card declined" message means that the issuer of the credit or debit card you have on file in your iTunes account rejected a charge or account confirmation. It is not an Apple problem; Apple is just passing through the message from your issuer. There are a number of reasons the charge or verification might be declined:

• Apple is not allowed to accept credit or debit cards in your country
• The card is not recognized in your country
• Insufficient balance or account in arrears
• Account suspended for suspected fraud (not necessarily by you)
• Error in card number
• Wrong expiration date
• Wrong security (CVV) code
• Address in your iTunes account does not match exactly the billing address for the card
• The card was not issued in the country of the iTunes store
• You are connected through a VPN provider that does not terminate in the country of the iTunes store you are connected to.

Here is additional information from Apple→If your payment method is declined in the App Store or iTunes Store - Apple Support

Check this article and follow the instructions to learn how to update your payment method ☞ Add a payment method to your Apple ID - Apple Support

Hey there,

What happened when you try to update your payment method?

is there any error message?

Check this article and follow the instructions to learn how to update your payment method ☞ Add a payment method to your Apple ID - Apple Support

I have the same problem. I have tried numerous times. The error message I get is “you have not completed the entire form” but there is no indication as to what is not complete, there are only a couple of boxes and they are all complete. I have tried to update on my phone. It should not be this hard - every reply just links back to the instructions which I’ve already read and don’ t help at all

I don’t wish to be rude but that is the most unhelpful comment - I’ve already explained that the instructions DO NOT HELP. you clearly have not actually read my comment…

can't update payment card on phone nor i-pad.......same card card i use daily.