How do I provide a payment source to purchase additional iCloud memory?

See >>> Change, add, or remove Apple ID payment methods - Apple Support

If you only have a single Credit Card set-up for your AppleID account, you will need to add a new Credit Card to your AppleID account - after which you will be able to delete the old card details. 

It is often a good idea to have two (or more) payment cards associated with your account - as, in case there is a problem with your primary card, a charge can be made to the second card without risk of impacting ongoing access to your AppleID account or associated services and subscriptions. With multiple Credit Cards, you can choose the sequence in which card payments are made.

You may find these support pages to be helpful:

If you need to change or update your Apple ID payment method - Apple Support

Add a payment method to your Apple ID - Apple Support

Remove a payment method from your Apple ID - Apple Support

Payment methods that you can use with your Apple ID - Apple Support

Assuming that your payment card is supported, if you need assistance, you would be best advised to seek contact Apple Support:

Official Apple Support

it's the method of payment tired to your appleID

If you need to change or update your Apple ID payment method - Apple Support