Don't really think that L'Arse were cheated out. They did however, IMO play very well for the first 20mins until the sending off, with Valdes making a couple of good saves from Henry in the first 5 mins, then once Lehman got sent off, appeared to be hanging on, even moreso after they scored.
I do think some of the officiating was particularly bad, no bookings when there should've been, bookings when there were perfectly legit tackles etc, which did spoil the game a bit, but didn't seem to be really favouring one side or the other. Thankfully, said ref won't be at the World Cup, although I'm sure we can expect more dodgy refereeing