Why everything you've tried so far hasn't worked.
Portable units are three times louder than an installed system. They partially re-cool the air they've just cooled — so they're fighting themselves. The hose that has to hang out the window means your flat is never properly sealed. And every few hours: empty the tray or face a flood.
Fans just move warm air around. They create the sensation of cooling without actually reducing the temperature. In a flat that's already at 30°C, a fan is a comfort blanket — not a solution.
A properly installed system operates at whisper volume. It doesn't hose out the window. It doesn't need emptying. And it cools the room to exactly where you want it — and holds it there.
Worth knowing: Extreme indoor temperatures are medically dangerous for elderly people, babies, and pets — who cannot regulate their own temperature and cannot tell you they're too hot. Installing proper climate control is not a comfort upgrade. For many households, it's a health decision.