I have two diesel cars , have no problem at all , but I have a question
how often have you taken the car to service check up since you got the car ?

I have to go :

15:000 km - 30:000km- 45:000km-and in 60:000km and most likely your problem is the diesel oil filter is dirty along with the air filter , but also to save money and
diesel you should also change oil, if the filter is okei , then the pump is not pumping enough diesel oil into the engine . those are most likely the couses , I talked to a diesel fan for 50 years of hard Icelandic exsperience on the mountains , Good luck .

All the best Skarpi