Radiostat 6000 help please?

Hi, can anyone help with a link for the user guide for the Radiostat 6000 in my Megane. Or perhaps someone knows how to turn off the rear speakers so the kids can hear their DVD player and i can listen to music. I have worked out how to reduce the volume in the rear right speaker, i can't work out how to do the rear left speaker though. Any help would be much appreciated. Thanks for looking. :-)