SagePay Direct debit is a Splynx add-on. It used to customers be able to pay their invoices by https://sagepay.co.za/
Install the add-on with commands:
apt update apt install splynx-sagepay-direct-debit
or you can install it from Web UI:
Config → Integrations → Add-ons:
After that you need to registrate on https://sagepay.co.za/ . and configure your account.
After installation and registration you have to configure add-on params:
Config → Integrations → Modules list:
Here you can also set fee for customers:
After installation SegaPay, customers will see a new pay button on their invoices.
After pressing those buttons customers will see payment window where they have to confirm payment:
If everything went well, you will see status of invoice as "Paid" (portal and admin):