TOPIC:

I have a kadjar diesel from 2017 automatic gear. After an engine change 2 years ago it stopped heating on the passengers side. Only cold air comes into the cabine. I brought the car to the renault garage where they told me they must change the heating radiator and get the entire dashboard out. According to their saying they cleaned the entire water system because it was dirty creamy slime. After "repairing" the heater it only worked for 60%. And now a month later again only cold air on the passengers side. 
What might be the real problem and solution? I didn't think it should be such a difficult problem.