I was on Gusto for hair colouring, haircut and blow dry. I found a good offer on treatwell (£73) but when I arrived there the hairdresser told me that the prices were wrong on the app and if I want the blow dry I have to pay £26 extra. I was very disappointed as I consider that it not was my problem, indeed if they have a problem with the app they should call me before the appointment to let me know. In general it was a good experience but it was finally so expensive.
I would recommend to call them directly to check the prices and do not book by treatwell as then you will deal with unexpected charges. In my case, I am not coming back again as I know places cheepers even without offers.