Dad deal nissan

Bought a brand mew nissan np300 2.5 tdi last year 15 novenber 2019. From day one I complained about the vehicle smoking nissan germiston told me I should ride I for about a 1000km but no change it has been in and out nissan germiston since then and all they been doing is settings on the computer it went for its first service 15000 km and still doing the same thing it now has lost power and is not pulling right they say the bakkie right and can't fine any thing wrong with it since the can't sort it out I have asked to replace it but with no luck I am very unhappy as I trusted nissan I have bought a new bakkie which is not right and between nissan germiston and Nissan south Africa I have no joy please someone help me sort this problem out or at least give me advice as what to do nissan customer care not helping at all