A very common problem I'm afraid, see BBC Watchdog:
http://www.bbc.co.uk/blogs/watchdog/2009/10/renault_get_lost_on_a_scenic_r.html
ECU Testing are probably the best place to get it repaired:
http://www.ecutesting.com/renault_megane_scenic_instrume.html
They guarantee their repairs for 2 years.
ChicksFan, May 2011