[Closed] Double glazed window won't open

We now have three windows that won't open. The handles turn but the window doesn't open. The first two were not really used so not an issue but the latest is regularly opened.

A quick google reveals the solution :

'sDiy

However I cannot get a thin paint scraper between the window and the frame, let alone an allen key. Looking at the other windows there are 4 bolts keeping the window closed, two near the corners and two near the handle in the middle. There is almost no flex in the window and I had to use a hammer to get the paint scraper even a little way in and even then it was just squashing the rubber seal which is about 1mm or less deep.

Any ideas how to proceed other than new double glazing?