I have generally used Carlton Cars, who until recently have been extremely reliable but the last two times I used them they let me down, one of those times particularly badly as I had pre- booked several days before as I needed to get a specific train to make a flight in time. Half an hour before the pick up, they called to say they couldn't fulfill the booking. I called Forest Hill Cars instead and they were there spot on time. They also bailed me out on the second occcasion too so my recent impression of them is pretty good. While I absolutely agree that swearing at a customer is not acceptable, I also agree with others who have said it isn't really fair to overbook taxis with the intention of cancelling.