False adverting

Nissan advertise that the Nissan NP 200 *****th comes with leather seats. On line adverts and the Nissan brochure state leather. Absolute lie. Our son bought a NP 200 *****th in 2015. The vehicle has 30000km on the clock with full service history. The seats are finished. The plastic covering has peeled off completely on the driver's seat and the passenger seat is starting to peel. At 30000km I find this disgusting. Vehicle was purchased from Atlantis Nissan and after inspection by the service manager, a claim was lodged with Nissan HO. The claim was rejected. How can this be on a vehicle still under warranty.