If those extenders are hardwired back to the router then they'll probably be access points rather than extenders. They don't have LAN ports on the back you can access do they? You might be able to sneakily run a cable from your nearest one into your room, effectively wiring yourself to the router
As an aside if the whole communal house is connecting to the same router then I hope you have an appropriate firewall in place covering your devices otherwise you'll potentially be leaving yourself open to people who share the WiFi. Maybe they've implemented VLANs to mitigate this but I'd expect you to either have to register your devices with them, use some sort of captive portal or everyone to have their own bespoke SSID/password combo for that to be in place.