Good luck! Feel sorry for you...
Spoken like a true 'expert' who really knows nothing. Miller's and Forte are NOT the same stuff and are nothing like each other and are definitely nothing like Redex which is a snake oil. Stick some Miller's in your diesel car and do about 100 miles for it to really kick in then come back here to comment.
Although Millers does improve the cetane numbers so you get much improved combustion, a cleaner burn and thus less emissions, better fuel consumption. Modern diesels do need driving at high revs for a few miles occasionally to clean out the exhaust by getting it red hot and thus burning any deposits.This also helps to clean the exhaust gas recirculation or EGR which causes a lot of problems in modern diesels.
Millers or Forte are the same stuff , just different name....so all you waisting money .... If problems with emissions- just do Italian TuneUp without any additives and you be good.
Millers is an excellent choice to keep the diesel fuel system clean especially if you do a lot of chugging around town ( I was doing 30,000 miles a year city/town driving) It not only improves the power but if you're using it in a car the difference in engine noise is very noticeable after a week or two of first using it the engine is so much smoother and quieter.