Condensation in double glazing

[Elliptic5]

After nearly nine years quite a few of our south facing double glazed units appear to have broken down, including top openers and the larger windows. The firm who installed them shut last year and there appears to be no guarantee or registration with any trade insurance mentioned on the original paperwork.
This has come after we spent several thousand pounds only eight months ago having scaffolding erected (over a full length conservatory), a lot of wood weatherboarding replaced and all the windows repainted. I assume any repair will need to be done from the outside necessitating more scaffolding.
Is it normal for double glazing to break down like this? Do I need to look at replacing all the windows as I can't keep having scaffolding for a few windows at a time? Is it because they are south facing? And I have I just got to swallow the cost or is there any comeback on anyone? (we are in Scotland).
I'm just not sure how we are going to afford it

If you have had the windows repainted then I assume they're wood. If so, then it's a fairly easy job to get someone in to replace the glass units. We had this done 18 months ago and they did the first floor ones from inside the house - our windows are fairly small though.

Our south facing windows were far worse than others.

Yes, wood - forgot to mention that. I was thinking that the new paint would be damaged replacing the units so, even if that was done from inside, I would still need the scaffolding for the painter (mind you if we had scaffolding I would probably paint them myself this time).
Did you replace all yours or just the failed ones Stan? You have given me hope - perhaps its not as bad as I'm thinking.

When I say that they replaced them from the inside, they did it by either leaning out of the window, or taking the windows off from its hinges. They used a flat chisel type tool to remove the wooden beasing holding the glass pane. Damage was minor, but it did mean it needed touching up.

We replaced all of ours and then I touched up the paint/woodstain via a ladder.

When I say that they replaced them from the inside, they did it by either leaning out of the window, or taking the windows off from its hinges. They used a flat chisel type tool to remove the wooden beasing holding the glass pane. Damage was minor, but it did mean it needed touching up.

We replaced all of ours and then I touched up the paint/woodstain via a ladder.