Injectors need to be calibrated so garage, be careful as it is easy to misdiagnosis which is at fault as it can look like one is at fault while another trying to compensate another. Has a leak back test been done?
I would offer to look at you but we are a long way from you, I would advise to look for a Bosch diesel specialist local to you
I took car to LC Motors in Newport a franchised Fiat dealer who has worked on AO'ers Alfas several times, they plugged the ECU in and it diagnosed an internal fault on Injector 1.
Symptoms:- Am getting very rough idle and very hesitant between 800 and 1500 rpm once past that all ok also had to coax 2 x regens in last 6 weeks I suspect due to increased soot from Injector 1 misfiring. LCs quoted me £220 for injector + labour 1.5 hrs @ £75 / hr so I am keen to try and get it done for less if possible. have seen injectors for £75 on Flea Bay but not checked if new or recon.