Sprinter drive noise still there after changing diff bearings

Had the sprinter in today, it has been making a whining noise when decelerating all the way down to being at a stop.....its the semi-auto box on a 311, 55 plate.......first of all, they found the diff bearings were rough and replaced them...but it still made the same noise, so they opened up the gearbox and found no problems in there....the only other thing he suggested but could not be certain of was the crown wheel and pinion bearing....could this be the problem? just spent nearly 800 quid on all that today so need to try n clarify before i go ahead and get it done.

He did look at the crown wheel when doing the diff bearings but he said sometimes u cannot see problems on it with the naked eye.

any ideas?

thanks, ian