Hello Jackson,
I have used QuickBooks Payment Gateway Module for my WHMCS store. This module is very easy to use and supports credit and debit card payments across different countries United States, Canada, United Kingdom, Australia, and New Zealand.
The best thing is, you will get 7 days free trial before buying the premium version here.
Get it from here - https://members.modulesstack.com/index.php?m=product_page&pid=18&name=quickbooks-payment-gateway-for-whmcs
Let me know if you need any assistance.
Thanks