Clio EDC Gearbox Oil Leak

Does anyone have a video showing how to top up gearbox oil on a Clio EDC? I have a patch on my undertray where I’m getting a small leak from directly under the gearbox not a huge amount but definitely leaking I’ve had a specialist take a look who couldnt find the issue only to just keep topping it up, the drive shaft seals seem dry it looks like where the box is joined together underneath maybe, The car is on 55k miles maybe I should think about selling it now?
 
to top up jack up passenger side. remove wheel. next to driveshaft is a white plastic wing nut style cap. unscrew this and fill up with dc0/dc4 oil from renault till it leaks out then refit the cap.