Your window may have a restricting device that limits how far it opens. Its there for your safety so its important that you don't disconnect or damage it, or let anyone else do so. If the window fittings do become damaged, you need to tell a member of the property team straight away. They check all the windows and their fittings regularly, to make sure they are all safe and working properly. Depending on the floor you live on, it may be possible to derestrict your window upon request and with approval from the management of your property. Please speak to your reception team.