You can change the payment card that you use to pay for your subscription from the Account Details -> My Subscription page at https://www.seatspy.com/user_subscriptions.

You can navigate to this page by logging in to your account on the SeatSpy site and clicking on the Account icon at the top right of every page. Choose the My Subscriptions option from the drop down menu.

This takes you to your Subscriptions page that will list all of the detail about your current subscription, including the card you are using to pay.

In the Payment Method section there is an option to "Update Payment Card Details". as shown in the screen grab below Clicking this link will let you update your card details or change to a different card.