Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

Hi guys, I need help to fix this aggravating problem I have. I live in a tropical island and have a Corsa B. The previous owners had the car in poo condition and the slider/cable for the recirculation isn't there. I believe the vents are open because if passing through any smoke etc the scents full up the car. This is causing a problem with my AC in scorching hot weather because I know those vents need to be closed for proper function of the AC.

So my question is....how do I get to those vents to close them off seeing as I can't with the slider?? What exactly do I need to do? I need to get this done asap as the sun these days is unbearable. Thanks a lot in advance for any advice.