Gap between plasterboard and velux

[chris.waring.wolves@gmail]

Hello,
Long story short we had a bad builder incorrectly install a pitched roof on an extension. A good builder corrected the roof which included using thicker battens. The result is the velux windows have now lifted leaving a 1cm gap between the plasterboard and velux window frame. There is a bit of a draft coming through the gap.
what is the best way to fill this gap? Or do i need to re-plasterboard the return entirely?
thanks in advance.