I'll spare you the full details for now, as I'm still arguing with them, but the elevator version is that we booked on a family group tour, flights inclusive, so that there would be company for our son, but there were no other bookings so we were offered an alternative, which we accepted. It was only when I repeatedly emailed asking for details of the flights that we discovered this slight problem. I've demanded a full refund but I have a feeling they will try to make us accept a credit against another of their holidays.
And, yes, I do think this would be one for the consumer media if we get nowhere, as this is a well-known company.
My bigger concern at the moment is to organise something else for half-term!