If you are seeing the "Sorry! An error was reported from our payment processor (Declined)" error when you are trying to update your payment method and pay, it's most likely caused by the reason that your bank is unwilling to accept the transaction. You can read more about "Processor Declined" here.
In cases like this, you can get in touch with your bank regarding this issue or use another card at the checkout (if you have any).
If none of this helps, please reach out to firstname.lastname@example.org and we will make sure to find a solution for you!