the recal is on the tensioner, and the oil feed nozzle is part of the new kit, they dont want to open themselves up to major sueing so they dont directley say much about it. Like vovky says, get vauxhall to write on headed paper that:
"the cam chain will NOT snap on this vehicle due to a blocked oil feed nozzle or any other malfuction of component as fitted by vauxhall from new, thus making the vehicle unfit for purpose from the day it was built"
I bet they WONT write this, in which case you say "replace it then".