Nissan Extrail

Hi I have purchased a nIssan Xtrail 2018 brand new from CMH Durban. Before it went in for the first service, I felt a miss fire on the engine. I reported it and upon investigation Nissan found that the engine had carbon build up. They told me that they had to remove the head on the vehicle to clean up the carbon. After doing that the problem still continues. I reported this to Nissan and the team at CMH Durban could not find the fault. The problem got worse and when I insisted that they get a technician from Nissan have a look at the vehicle. They said that they need to install 4 new injectors. After this repair the problem never went away. They called the car back to clean out carbon build up again and replace the injectors again. This is when I refused to take the car back. Nissan has hired me a car in the interim. They supposedly repaired the fault and replaced another 4 injectors. Nissan SA gave me until 3pm last Friday to return the loan car as I was not prepared to take a loss of R65k for them the put me in a new vehicle. I picked up my car and 3days later, the problem surfaces again. I am not sure if there is anyone else experiencing the same issues. Please can I have some options.

Logan