Well I don't think there's anything you can report them for - it's not an offence to just mess people about, however annoying it might be. It being the school holidays probably isn't helping either.

Do you have a confirmation system? I'm strict with mine and very rarely have no shows - bar a couple last time I was in Ireland (and that's all) I can't remember the last one. Saying I can't talk and asking them to please ring back in a couple of minutes is handy too if you take short notice/same day bookings - the idiots generally don't bother .