DSE BMW 2.5 DIESEL ENGINE BAD STARTING HOT & COLD

I OWN A 97 RANGE ROVER DSE BMW 2.5 DIESEL
WHEN I FIRST BOUGHT THIS VEHICLE IT WAS BAD TO START WHEN COLD, AND STARTED NO PROBLEM WHEN HOT, TOOK IT TO A LAND ROVER DEALER ,REPLACED GLOW PLUGS (RELIEVED ME OF A WAD OF CASH FOR THE PRIVALAGE?) CAR STARTED NO PROBLEM WHEN COLD.
COUPLE OF MONTHS LATER CAR DIFFICULT TO START WHEN HOT,
AFTER PUTTING UP WITH THIS FOR A FEW MONTHS I NOW FIND CAR IS DIFFICULT TO START COLD & HOT , I HAVE REPLACED GLOW PLUGS AGAIN + FUEL FILTER STILL NO CHANGE?
DOES ANYBODY HAVE THE SAME PROBLEM OR ANY IDEAS AS TO THE CAUSE
MANY THANKS IN APPRECIATION OF YOUR ANSWERS

PS GREAT SITE

Have you had the ECU checked out, it might be displaying codes which actually tell what the fault is, only problem is to do that you need to go to a dealer.