hard to start in am 311 cdi sprinter?

it is a 53 plate 311 cdi sprinter and wont start in the mornings, I have to wynd and wynd and after running down two batterys it usualy starts. once i do get it started it will start no prob all day even if it has sat for 8-9 hrs in the cold, it runs ok when it is started. I've had the glow plugs changed it made no differance