I used to work in the industry and your seal around the glass has a break in it which allows the air in so causing the glass to mist up. I know people in the trade so if you have not managed to get it fixed pm me and I'll give you a contact.
we have this in two huge windows and one medium size one....quoted around £550 to replace them. we were thinking of perhaps looking at replacing the whole lot as they were all fitted about 20 years ago.
by replace, I meant fix the seals and replace the glass
Thanks people. I'll give my local Double Glazing Doctor a call, to come and have a look, I guess. Fingers crossed for a cheap fix, as otherwise it will join the garden fences and the roof tiles on THE LIST.