If you prefer to use your own interface for the payer instead of the ready-made web interface from Freedom Pay Gateway, you can use this method.
To get started with this method, you first need to use the Init method (described above) to obtain the pg_payment_id
Then, you can use the Pay method to initiate the payment process, and in the request to the Freedom Pay Gateway, you will need to pass the previously obtained pg_payment_id
