Mister Angry,
I regret that you have been inconvenienced in this way. Can I assure you that the priority desks have indeed been continuously manned every day including Christmas Day.
Obviously those desks cannot carry out engineering functions but I believe that engineering support albeit limited was available and that any concerns about availability of spares should have been directed to the Priority team.
There ARE folks at FLS who do actually care about Customer Service and are concerned when complaints such as yours are voiced.