how to update payment info for Netflix itunes?

I keep getting emails from Apple titled, "Billing Problem" with regards to Netflix

The content of these emails is:

"Dear [my name],

The charge for your subscription was declined by your [credit card]. To avoid losing access to your service, update your payment method.

Fix [credit card]

Regards,

The Apple TV Store Team"

However, this email provides no means to fix/update my payment information. The fix button in the email does nothing.

I would like to update my payment method, but do not know how to.