(You haven't mentioned the model)
First of all, the cost of maintenance for new cars is always on the higher side.
Secondly, all the diesel engined cars requires frequent oil changes than of petrol due to heavy contamnation of oil, than petrol.
Thirdly, the tuneup of a diesel far difficult than that of petrol due to more sensitive factors involved like diesel pump nozzles, advance/retire pump setting, diesel injectors(automisers), diesel and air filter etc.
"Please discuss" is a purely "Official" word and after each please discuss, a short 1:1 meeting is called