Thanks DanW. I'll let you know the fault codes when my garage tells me. I've found them pretty poor at communication generally. Not only did they not provide the evidence that prompted them to conclude the injectors were at fault, they didn't give me the injector test output, in fact they've not even had the printouts from the diesel specialist they sent the injectors to.

After refitting the suposedly reconditioned injectors the engine still didn't run properly. They still thought it was the injectors so sent the car to the firm that did the reconditioning. Now the car is back with them they say there is a mechanical fault. I'd certainly not have approved the injector work if I'd know there was another as yet undiagnosed fault. I now don't really know what to do.