How can I update payment details

There are, at least, two possibilities at play here:

• All of your payment methods are from financial accounts that have been suspended due to any number of reasons. Try another credit card that you may have.

  Change or remove your Apple ID payment information - Apple Support

• Your Apple ID has been compromised.

  If you think your Apple ID has been compromised - Apple Support

Hello,

Is it a legit email from Apple? It sounds like it may be a phishing email.

More info here:

Identify and report phishing emails and other suspicious messages - Apple Support

Once you have confirmed it's a legit email from Apple, follow the article above.

You're welcome! That may be a phishing email. I've haven't received any emails from Apple with that email address that I could find. I did receive one without the underscores ( _ ).

May I ask how you are changing your info? Is it on your iPhone or on a Website?

... and that would appear to be legitimate as the notification should be coming from Apple.

Try using a Mac and, using a web browser, go to Manage Your Apple ID. From there go to the Payment & Shipping section. Then click on Edit Payment Information...

If you are unable to update your payment information, you may need to contact your financial institution to find out if there is a hold on your account.

Payment methods you can use in the iTunes Store, App Store, and iBooks Store - Apple Support

See if the following Apple Support Communities post can help:

Invoice from no_reply@email.apple.com? - ASC

I'm glad you got it resolved ... and thanks for providing the solution that worked for you so that others, who may come across the same issue, can give it a try as well.