After your appointment is booked, it's not possible to change your method of payment or credit card.

However, you can change your method of payment when you book a new notary appointment.

Here's how to do this:

1. Log-in to your Notarize.ca account and click on New Appointment.
2. On the Client Information tab, next to "For payment use", select "New Card"
   
3. Enter in your new card details, then proceed to book your appointment as usual. 

If you are no longer able to use the credit card with which you booked your notary appointment, you can cancel your original appointment and book a new appointment with the correct credit card.