I waited for over an hour, to continually be told it was just another 10 minute wait, when clearly it would be much longer. Never actually got to the haircut in the end, as when we questioned it, the staff were rude and unapologetic.
I would expect any proper company to simply let the customer know that you are fully booked, and try to organise for a more suitable time to return, rather than wasting someone's time by having them wait around for absolutely nothing.