The Pay by Bank app code acts as a unique ID for your payment transaction. When your customer confirms the transaction amount, the system will recognise this ID and charge your customer the correct amount.
If for any reason the payment page is not automatically opened when the customer authenticates in their mobile banking app, when they click the link in the SMS text message, they can also manually enter this code into their online banking application with Pay by Bank app in order to process the correct payment.
The Pay by Bank app option should be visible in their mobile banking app as an option (e.g. Pingit below)
and once selected there is the capacity to enter the Pay by Bank app code to retrieve the transaction and confirm payment.