I’ve not been able to download applications, it kept saying I should update my billing information.

Log into your account in the App Store/iTunes and you should be able to change/verify it there. Or you can click the blue Edit payment methods in the article below. When signed in and the page loads, you will be on the credit card page. After updating that, click the Go Back button at the lower left and you will be on the address page.

Apple ID payment information - change.  

How to Fix “Verification Required” for Apps Downloads on iPhone and iPad   

See If you see a message 'Your account has been disabled in the App Store and iTunes' https://support.apple.com/en-us/HT208856. This link says: "There might be a problem with the payment method that you have on file. When you see the message, don't try to edit any of your account information. Instead, contact Apple Support for help.”

Try using the Apple recommended support link above first. But, this site is down/not fully functional very often. Use the support options I give below if necessary.

You can use Apple Support Twitter https://twitter.com/AppleSupport  There may be a wait of an hour or so.

And, if necessary, go here to contact iTunes worldwide support via text or chat https://support.apple.com/choose-country-region/itunes After choosing your country, see the heading, Tell us how we can help.

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Also, see

If your payment method is declined in the App Store or iTunes Store https://support.apple.com/en-us/HT203005.

Fix ‘Your Payment Method Was Declined’ Error In App Store https://www.addictivetips.com/ios/fix-your-payment-method-was-declined-error-in-app-store/

If you need additional help, use this support link from the document https://support.apple.com/contact  or use:

Apple telephone support  for help in solving your problem using this link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362 Be patient sometimes Apple support is closed to immediate phone support.

Apple Support Twitter https://twitter.com/AppleSupport There may be an hour or so wait.

iTunes worldwide support via text or chat using this link https://support.apple.com/choose-country-region/itunes After choosing your country, see the heading Tell us how we can help.