Sometimes they are on waiting lists for a long time and are then told they were waiting in the wrong queue, or have been knocking on the wrong door all along.
Weithiau byddant ar restr aros am gyfnod hir, dim ond i ddarganfod wedyn eu bod wedi bod yn aros yn y ciw anghywir, neu'n cnocio ar y drws anghywir o'r cychwyn cyntaf.