where's my dolby digital.

i have just added virgins HD movie package,it looks stuning i hooked up my samsung V+ HD box to my home cinema amp via optical settled down to watch a blockbuster and out comes poxy pro logic, i made some ajustments even feeding sound and vision thru H.D.M.I. a.k.a blu -ray but i'm still not getting 5.1(dolby digital) what the hells going on, i know i'm not going to get any of the new HD sound codecs but i was hopeing for a dolby digital decoder and transmissions.now i'll have to wait a month to get shot of the films and tredge back up blockbuster for the supperier blu-rays. virgin really are assholes.