I’ve never seen a wall plate dimmer rated at over 400W, 350W running off the one in our living room and they don’t last that long even at that.
once you start getting into the 400W plus range your talking more heat than a wall plate can accommodate. You’d need to install a dimmer device in the roof space and a control plate on the wall.
Solution would be to fit lower power lamps.
I’m not really think i’ve seen a room in a normal house that actually requires 550W of halogen lighting, that’s a lot of bright!