Why according to Rousseau representation always illegitimate

It allows someone else to make your choices
The claim 
	You chose that person who makes laws for you 
is unacceptable.
Either the choices are yours or they are not
	there is no room for compromise

This is not just an abstruse point 

Representatives may express their own will 
	sometimes we praise them for this; sometimes, blame them. 

We speak of someone as being ahead of their constituents
	this may in practice be a virtue, 
But how can a democratic thinker justify it in practice?

Maybe the result better, perhaps worse Certainly not expression of will of
represented

Rousseau's claim today is highly counter-intuitive, for we link representative
democracy and freedom.