Agree with, "FLEXJET"
Delt with too many passengers who just didn't read their terms and conditions before buying, and get angry when those conditions are followed to the letter.
This occurence does seem strange, Ryanair now have 2 spare a/c based at Dublin and Stansted.
And Dublin operations do attempt to sort the problem.
I think there are probably other circumstances which your parents were not advised about.
Johnny