This switching of ML / WL is obviously low business ethics

Firstly lets assume the person you booked is actually rostered at the shop on that day. Some shops are advertising and the lady is not rostered

Secondly with a shop you don't know enough to trust, if it's important to you, ring 60 minutes ahead of time to confirm first that the lady is working, and that she is definitely ready for the booking

If you get in there are they still have stuffed up your booking, stay very calm (as you may become a regular customer)
Tell them you drove in the traffic for an hour to get there, and you took time off work.

Ask for a discount, or fix up the issue as soon as feasible. Ask if there is a better lady available, ask for whatever is reasonable to fix up the issue. Be sure that other punters listening are aware of your stuffed up booking despite confirming a definite booking

We are talking about $200-400 of money changing hands. This is a significant service you have organised, it's not an ice cream you ordered off Menulog.

You get your car serviced for this kind of money. Imagine you drive your car to the garage for a booking at 12pm, and they tell you to come back in an hour, that noone can help you. No, a mechanic wouldn't treat you like that, you have a booking. Get real

The brothel manager on site needs to be answerable and sort it out. Amateur booking systems are not acceptable