I have had the octy2 over 9 years and done 200k nearly. Suffered badly from internal fog of windscreen for years outside weather permitting. 

I have cleaned the screen regularly. Not really applied any treatments as none are shown to be trustworthy. 

Well recently tried the actual button to clear it and it's pretty quick, bear in mind my aircon does not work at all on my climate control, been like that for a couple of years now.  

The top button which although I wish was heated front screen like my Superb actually does clear the screen reasonably quickly, I used to just direct the air to the screen with the other button, next to the passenger temperature which shows a screen too . 

Correction it's the button top right next to recirc I usually use. 

Left car for 1 hour and on return front screen and rear screen misted again. I do have pingi bags maybe need a recharge too. 

Edited 9 February, 20188 yr by gav_is_con

clean you glass with AG glass polish, apply FOG-X

 

if this doesnt sort it, steak looking for water ingress

I use this technique and it appears to clear the fogging quicker! 

 

 

Often the reason for interior fogging is that the recirculation flap valve is stuck, so there is no fresh air coming into the car and the humidy will keep rising as the occupants breathe. This high humidity air condenses on the glass and elsewhere when the car cools down.

Once the valve has been fixed you can dry out the car by keeping the climate control or air-con on once the outside air temp is above 5C. Works very quickly too in rainy weather. Many people forget that with climatronic systems you can have heating and air-con selected together for humidy control without it changing your set temperature. But recirculation must not be on.