After making your down payment Stripe may store your credit card to use later for paying your final / remaining balance. This may make it look like our system will now allow you to change your billing method. But you can change your payment method by doing the follow.

Start by entering your email address. After entering your email address you may be prompted to enter a code (that will be emailed to you) to use your stored credit card details on file. Click the box stating you didn’t receive the code and you will be prompted to enter your credit card details manually. 

Click, Fill in card details manually. Enter your updated credit card information to pay your final payment using your preferred credit card.