upvc Window bent/deformed?

[bilbob]

Hi all,
Hope you can help me!
I've got a couple of windows that have gaps in the seal at the hinge end where the opening window meets the frame.
Now I've read through, and I know that it in itself isn't uncommon, but I think my situation is slightly different.
When closing, where the hinge end of the window meets the frame, there is an uneven-ness about the line where they join, at the top and bottom, it is coming to close, but in the middle of the vertical, there is a larger gap. I've measured, and it is clearly the window that is bowing. It's not severe (I think..) is there anything that can be done?
Is this normal? Can I compensate by closing the hinges more? Or is it simply a case of replacing the whole frame, or can I just replace the opening frame/window unit?

Thanks for any advice!

 

[Nooz]

Depending on how it was fitted, and I'll try to be polite, it's not unknown for the fitter to pull the frame in whilst they are fitting it and twist the jamb so it doesn't meet the gasket . If this is the case in the past I have cut out the old silicon, loosened the fixings, packed the window jamb straight and tightened and resealed the window.
A few pics might help if possible just to confirm.

 

[crank39]

May possibly need closing wedges, not uncommon for the middle to bow away