As far as I know, if the wipers are acting like variable intermittent, i.e. same amount of time between wipes depending on the collar setting, then either you car does not have rain sensing wipers, or they have been set to variable intermittent somehow (don't know how this is done, but would be interested to know!)
Our Scenic II has rain sensing wipers that do not work because (I think) someone has removed the 'optical bond' between the sensor and the screen. Basically they make one sweep when you turn them on, then do nothing. They also make one sweep when you change the collar setting and then do nothing again.
Currently in martin999's garage:
2011 (11) VW Passat 2.0 TDi SE + options in Island Grey, 2011 (11) Honda CB1000R in Pearl Cool White... oh and a 2004 (54) Secnic II 1.5dCi Dynamique in Ottoman Blue !