Your post reminded me to at least go and check out my information, (credit card expiration/update) and my personal info, since it had also been a while since I'd done that.
Just now, I went onto my account page, and was able to quickly update both my credit card info and some address information on my main account page, with a couple clicks.
After making the changes on each page, I hit the "Submit" button, using my HA password as the credential to verify my info with.
I also immediately got 2 auto-generated emails from HA, informing me of the successful changes made to my account.
So, it's very weird that you seem to be having such an issue with this. Hope you get it sorted out.