The best one I had was when the guard said I apologies for the continuing delay, which I don't have information on. When I get it I will let you know.I always used to use 'Operating incident' if i didn't know the cause and the control number was engaged 'frequently' and all the emails/texts we received were about booking offices closed or PERTIS machines not working.
Sometimes you had to be creative to say something when you knew nothing.
Whilst that's not the only time, it's the one that sticks in my mind the most.
What also sticks in my mind is being hold outside Woking with no explanation or word for the guard at all and missing my connecting train to Guildford.