In February, waiting for departure from JNB to GRJ on a SA Express flight, a CRJ I think, captain announced that there was a problem with a cooling component on one of the displays and that this would have to be checked and possibly replaced if not immediately repairable.
He kept us fully informed all the time, with good humour and wit, without being patronising, and told us that in the worst case scenario we'd be put onto a back up aircraft, and that there was one available.
The cabin crew kept us supplied with refreshments and and when we were finally transferred, via the lounge, and onto another aircraft, there was no moaning and groaning, and we only arrived an hour late.
I realise that this was an almost ideal scenario, small aircraft, not full, home airport, etc, and they had everything in their favour, but I have been in similar situations that were appallingly handled, text book examples of how not do it. Iberia in Madrid comes to mind.