iPhone 17 Pro One time Pins issue

I can only speak to the bank app, but it follows that the other apps do the same procedure. Banks are the ones that send the OTP, not Apple. At some point in the past her phone number changed. The bank still has the old number as the primary contact number and that’s the number their computer pulls to send the OTP. I suspect the other companies are doing the same thing. She needs to contact the companies customer support teams and get her >> primary << phone number updated.

Ask the woman if she ever changed her phone number. It could have been 5 years ago, 10 years ago whatever. Changing the number in an app or a website is not sufficient for a bank. The customer must make voice contact to change a primary contact number.

Ask her when the last time she changed her phone number was.

Here is a paragraph from Apple’s documentation on bank issues.

Adding additional verification

A card issuer can decide whether a credit or debit card requires additional verification. Depending on what’s offered by the card issuer, the user may be able to choose between different options for additional verification, such as a text message, email, customer service call or a method in an approved third-party app to complete the verification. >>>For text messages or email, the user selects from contact information the issuer has on file.<<<

A code is sent, which must be entered into Apple Wallet, Settings or the Apple Watch

app. For customer service or verification using an app, the issuer performs their own communication process.

Card provisioning security overview - Apple Support