Looking at her pricing it's highly likely to be a conveyor belt operation with double bookings as you mentioned. Booking appointments is a waste of time at that price range, better off hoping they are avaliable when you are in the area or do not bother at all. That's part of the reason I don't travel further than necessary regardless of how "great" the service is in regards to value for money if the price seems a bit low, odds are several punters are also trying to try their luck. Especially now there are a couple positive reviews to her name. Better luck next time.