repla*****t of diesel pump

In Sept 2011 I bought a new Nissan Navara 2.5dc1. It was on a service/warranty plan for three years. It went on its service every 15000km.The last service on the plan was done on 59568 km on 23 April 2014, on 61000km the vehicle just cut out on a speed 60 km/h.The next day I phoned them and explained the problem on which, I was told to bring the veh in so that they could determine what the problem was.They fixed the veh and according to me, as told by them it was the diesel pump that was faulty and they replaced it. On 29 May 2015 the same problem occurred on which I phoned them again was told to bring the veh in and it was fixed. Less than a month later the same problem occurred and the Workshop Foreman phoned me the diesel pump must be replaced and it was only then that I learned they never replaced the pump as indicated by them, they only replaced a valve knowing that my warranty expires soon.They again only replaced the valve and the veh is malfunctioning again the same problem and they expecting me to foot the bill. I was left without transport all three times without them offering me a courtesy veh.The veh was given back to me they will only fix it if I pay half of the bill.