I'm not sure what I may have done to affect this, but it seems now whenever a user selects the offline option and proceeds to click through as instructed (i.e. the pink button & pop up message) followed by a pop up of the payment slip, nothing else happens.
That's working as it should. They're free to navigate away from there.
I seem to recall that the page redirected to a confirmation page but don't recall anymore. If not is there a way to set this up
The way it seems now, the user may be left wondering what's next.
Edit your offline payment gateway and change "Payment slip opens in" to "Stays in same window within the site, optionally with PRINT button" to send them to a separate page instead of using a popup.