Really??
From the Installation Manual
3. Set the central heating external controls to OFF. The burner should go off and the pump continue to run for two minutes.
If that's not pump overrun, what is it?
Well it sounds like pump overrun, but he did say it doesn't have it, I actually asked twice. As I said the terminal is there, it's shown in the manual but it doesn't show it connected in the diagram. Very odd.