Hello clinton283,
Thank you for using Apple Support Communities! I understand that you need to update your payment information used for an iCloud storage plan, however you are unable to do so and you do not recognize the current payment method on file.
Have you been seeing the monthly charge for iCloud storage on a statement from your financial institution? If so, is it possible that the card currently on file is an old payment method that's been since replaced by your bank? You may want to contact them to further explore this if you are in fact seeing the charge. If you haven't been seeing the charge for iCloud storage on your statement, I would like to first have you confirm that the email you received is legitimate:
Identify legitimate emails from the App Store or iTunes Store - Apple Support
You may then want to check if there are any devices that you do not recognize that are signed in to your Apple ID. If an unauthorized person may have access to your account, follow the steps in the second link:
If the email that you received was legitimate, and there's no concerns with the security of your Apple ID, add a new payment method to your Apple ID. Once you have added a new payment method, you should then be able to delete the other card with the last four numbers that you do not recognize:
Change, add, or remove Apple ID payment methods - Apple Support
Take care.
