Add a link to the statement which enables the customer to pay via the integrations (such as Square, Stripe or GoCardless).

This would ensure you are ahead of other accounting systems such as Quickbooks and Xero!!

The integration is there, there just needs to be a payment link on the bottom of the statement to enable the customer to pay by card straight away - people these days want speed (they don't want to have to log on to their bank accounts).