Possibly a burnt out connection, its very common. There was a design fault, too much current through the connector. If you've not looked already there are a ton of threads on the subject over on Renault Forums http://www.renaultforums.co.uk/ , look for a long one which has pictures of a DIY fix. Its a pain though - a Renault dealer would take the dash off and charge £500+ but if you've got skinny hands you might get access through a dash panel. It involves soldering in a section of replacement loom and a new resistor I think so quite tricky. My Scenic only has 2 fan speeds left.......

got it booked in to local garage on fri to be checked out,they think its resistor and quoted £130 + vat ,warranty firm have told be its covered so hopefully will get it repaired.will let you know.