My payment information is up to date but still says theirs a problem

Grace31788, Email from who? Could be scam phishing emails to get personal info from you.

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Grace31788 Said:

"My payment information is up to date but still says theirs a problem: I keep getting emails about iPhone AppleCare payment problems. But I’ve updated my payment information and it keeps trying to use the old card on file"

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IS this a message? Or is it in the GUI of your device? Apple wound sent your such a message --your see it in your iCloud settings. So, if a message, then it is a scam, and troubleshoot it on your own, referring to the following...

Troubleshooting Billing Info Message:

That is a scam. Apple wouldn't send you an a ransom-sounding eMail or SMS text message. So, what seems to have occurred here is a scam..

So, Report this Message and Secure your Info:

Being account accessibility is of big concern here, (I.)report this message, and (II.)secure your account.

I. Report this Message:

So, report phone call's and messages info to Apple and others (such as your government). Use my User: Using the Photos App to Report Scams - User Tip

and...

II. Secure your Info:

A. Verify your Devices:

Verify that all devices are logged in to your account, by using this link: Check your Apple ID Device List to See where you're Signed in - Apple Support

then...

B. Modify your Credentials:

Having received this, someone may have your credentials. So, by all means, consider modifying them...

• Modify: your login credentials (Using Both a New eMail and a New Password for each and all sites)
• Associate: a different method of payment to your account
• Enable: Two-Factor Authentication for Apple ID and for all other accounts that have such an applicable option