Wexcan you are not automatically entitled to your money back if you do not get onboard the aircraft before groups A + B.
Remember that if you are on a remote stand taking a bus, the T&C's stipulate that you are only guaranteed to be on the first bus.
Also, you have the SB pax who think that they have time to go duty free shopping and that they will still get on the aircraft first. These pax most certainly will not be entitled to their money back!
Remember it is only Customer Services at Hangar 89 who can say for sure whether a pax is entitled to their money back or not, which is why the SCCM must FER any boarding irregularity that might happen. I am always logging problems with stands 1 & 11 at LGW for instance where the airport infrastructure does not allow speedy boarding to happen. This is the only time I can say for sure that a pax is entitled to a refund and I put it on my FER that way, but I still won't say to the pax that they are entitled to one as only Customer Services can say that.