I have had the same problem with my 2012 Premium. I bought it second hand in December 15 with 27k on it but it is obviously outside of its warranty. My rear NS indicator with flash rapidly on the dash and if you look at it from the outside then it will be flashing rapidly and eventually stop. Once the fault occurs it will remain for the length of your journey but if you leave the car for a few hours then the fault will dissappear, sometimes for a few days, sometime for a few weeks.
I am going to take the unit off today at some point (weather permitting) and try to clean the contacts to see if that is the cause. Dint really want to be spending the money for a whole new unit.
