UPVC casement window stuck shut; locksmith?

[DiscordiaVanDiemen]

Hoping for some window advice!
My flat has all UPVC windows, mostly sash, but one casement that opens; or rather doesn't open with a handle (with a keyhole in the middle of the handle) The mechanism is broken (handle feels "floppy") and window is stuck closed.

Does anyone know if this is a job for a locksmith or a "window repairer"?
If the latter, where would I find such a thing? (I've seen ads for companies that install new windows, but that's not what I want - also gather, from what I've read, that some of these companies are a bit dodgy and employ hard sell techniques, which would really irritate me!)

The other windows (sash) also have issues incidentally (one has the whole lower half falling out whenever it's opened and has to be clicked back into place) so I could do with someone looking at the lot - but the casement window is my priority as I hate not being able to open all the windows.
They were all installed about 6 years ago when the flat was renovated apparently.

Watching with interest; I have a similar window but it won't shut!

Oh Wish I know I'm lucky that it gave up while it was in the shut position!
I knew the handle wasn't engaging properly for a few days before it actually stuck!

Discordia, although I like my windows open too, I was definitely wishing it had stuck shut when the local teenagers were throwing snowballs through the gap recently

Just ring one of the local big double glazing firms and they'll have a repair person who they'll send out (for a charge) - that's what we've done successfully. You don't have to have their windows, although if you know the original installer that would help.

Thanks Hassled !
Wish

I'd ring a local window fitter, not a huge firm. Exactly the same thing happened to one of our windows-luckily a family member is a window fitter and fixed it in 5 mins by replacing the locking mechanism. Whoever you get to come, don't let them convince you it's a big/expensive job!

Thanks PipnPosy