I have a 2009 vito 639 LWB rear wheel drive van

trying to replace the nearside front wheel bearing.
Manage to strip it down, took the blanking plate off, but there is no nut to undo.
am i right in saying that on the 639's you have to get the hub and bearing as one unit.
but then saying that why do they sell you a bearing for it and you can't fit it!!

has anyone come across this problem?

thanks in advance
Mick.