Nissan Navara 2014 Problems

It is an often reported problem with the Navara. It's too late to fix your car, but it's important that the sump plug gasket is replaced every time the oil is changed, and that the plug is not cross-threaded when installed, which could have happened at a previous service on your car causing it to jam in the thread, and that it is not over-tightened.

Talk to the dealer and request that Nissan send a tech rep to inspect the car with you, and then work out a plan of action for Nissan to address your concerns. Nissan cannot walk away from the problem; you are perfectly entitled to demand they fix the car. If it can't be fixed, then I think you have good justification for asking for your money back.