o/s rear window wont work 54 megane 20ltr cab?

HELP PLEASE IF YOU CAN,MANY THANKS
I have a 54 plate Megane 2.0 litre petrol cabriolet and my rear o/s window wont operate with the drivers switch or the rear switch for that window,but however it will work with the center console roof open/close switch and window switch(the one that operates all 4 windows on center console),I have checked both the 20 amp fuses and the 3rd 40amp fuse,and they looked fine,the left windows and drivers windows are fine,any ideas what it could be and how to fix it,and what the costs may be please.????????????????