once fixed- i would get a note off the repair/diesel specialist detailing the fault and go back to main dealer claiming the money back for your "repair"-they simply didnt do the job required of them-if they refuse contact trading standards,all it takes is a call from them and they will re-look at it
as mentioned in this thread the main dealers can be[not always though] shocking in their incompetence

one thing a lot of people [never tried myself yet] rave about is terraclean for injection systems,its like fuel system applied seafoam -perhaps worth a try if ever faced with 4 injector replacements again