Calculate advance payment

How can i display only an extra cost without adding item price? Example:

Product cost: $1000
Subtotal: $1000
Advance payment (30%): $300
Total: $1000

I need use it like an advance payment notification.

I don′t want the plugin add the product cost to the extra cost, only display the percentage.

Does exist any way to get this?

Thankyou!

https://www.ads-software.com/plugins/woocommerce-pay-for-payment/