Definitely check the battery. I am a Megane GT owner from new 2016 model. My car has done 145klms now and I have had no issues with my gearbox. But when my battery was on the way out one time I reversed and couldn't engage into drive. It turns out the battery was causing these issues. Get the codes cleared and drive the car in normal and RS mode. I have heard from fellow enthusiasts that live in Europe there are issues with the gearbox sometimes. I guess it's the luck of the draw. Good Luck.
Sound like you have a nice car there mate. I will let you know the next track day I will be at. I mainly do time attack and sprint both at Lakeside and QR. I also have a really good mate that organises breakfast and laps.
Welcome Adz , If your keen to take your car on the race track let me know . We have a great group of people doing track days in Qld . The more Renaults the better.