If your prepared to do the work yourself i.e. remove old windows send templates away etc which inst that hard, (I did this from Spain) then Seaglaze in Norwich are very good and very reasonable.
I had them remake the windows on my P560 in aluminium.
If this is leaks on your Freeman, just remove the black plastic infill to expose the securing screws. Turn each down as far as they sensibly want to go and you may be OK.
You could also try some creaking cracks for minor leaking.
The black fillet can be stubborn to re attach but is supposed to be a press fit.