Hi there and welcome to Just Answer, my name is Richard and I look forward to helping you.
I’m sorry to hear you're having trouble. I know that can be frustrating. Hopefully, we can get this resolved quickly.
To update the details via your computer on your Amazon account.
To do this, please do the below steps.
Visit the page for your account - https://www.amazon.com/manageyourkindle
- Log into using your Amazon account (the same Amazon account you have registered on your Kindle)
On the right side select "Settings"
Under 'Kindle Payment Settings' (first option)
Click 'Edit Payment Method'
Change your credit card details.
Restart your Kindle and it will update
It will then be updated
If you have any problems, or would like any additional information or assistance, please do not hesitate to let me know.