Hi Harry,
I assume you are talking about condensation on the inside of the outer pane. If this is the case, the double glazing unit needs to be replaced.
This is caused by the seal being broken which allows moist air between the panes which eventually overwhelms the water absorbing material within the double glazing unit.
Do your neightbours a favour and let them know what the situation is, as it is unlikely that George Wimpey Homes will.
Let us know how you get on
Tony