Change credit card for subscription

I just figured this out and the answer was in front of me all of the time. I went back to the original email from Dell and saw the instructions right there, for Microsoft 365 consumer product:

Click Dell Digital Locker

Use same email that's on the current communication communication

Click subscriptions menu

Click add/change/update (one of these) and you are on the correct page to make the change.

Hope this helps.