The simple module allows showing Credit history so they can keep their eye on how the credits are being applied.
The best place to start if you need help with a specific product is to contact the developer. All WHMCS Marketplace developers have both a website and support URL listed.
CleanHTML Invoice and Quote Free template.
As WHMCS does provide tax rules options where you can configure your GST tax but we have some extra features in our module that makes it stand out and necessary to use.
Send account statements to customers
Automatically pay commissions to your salespeople, resellers etc.
The definitive solution for all your billing needs plus a lot of additional features