Shop Pay Installments - How to do a manual payment?

They have two options if you want to pay manually.

In the Shop app:

1. Sign in to the Shop app. 
2. In the Home section, tap the purchase that you want to make a payment on. 
3. Click View installments. 
4. Tap Make a payment. 
5. In the Amount to pay section, select your preferred option.
6. In the Card section, tap the payment method you want to use. 
7. Tap Pay now. 
8. Tap Continue.

In Shop Pay on your Desktop/Laptop:

1. Sign in to your Shop Pay account. 
2. From the Home page, select the purchase that you want to make a payment on.
3. Click Make payment. 
4. In the Amount to pay section, select your preferred option. Note: If you type a custom amount, then it must be more than one dollar and less than or equal to the total remaining amount. 
5. In the Card section, use the drop-down arrow to select your preferred payment method. 
6. Click Pay now. 
7. Click Continue.