Not sure if your experience was a Bait & switch since she did tell you she was not her...if the referred friend was not appealing you should have left after she opened the door...did you asked the replacement girl her name? if you have her name you can research to see if she is indeed a provider or you should ask the original girl who her friend was, so you can post a review.

have went through with the session.
The other "provider" was already there and that tells me that it was premeditated. She could have given you the choice long before you arrived, but she figured the little head would win out. She was right.

I would review the provider who you had booked with and explain in the review what happened. I believe that would be within the review guidelines.
Otherwise, you should be naming the provider who pulled off this stunt.

I know it's difficult, since the little head is ready to go and you had a good enough experience with the lady to book this second appointment. You cannot write a review of the originally lady, but you can write a review of the friend if you have the minimum info to meet ter requirements for review purposes.

I would leave immediately simply based on the fact that I would be way too concerned that my original provider had been compromised and I was now in the presence of LE.  It would just freak me out too much to go on with the appointment.

I am pretty thorough in my research and need to feel like I am seeing the person I became familiar with.  I don't TOFTT intentionally or unintentionally.  That is for the braver souls among us.  

Which BTW I am grateful you guys who are out there searching for the hidden gems and are willing to TOFTT.

RK

The name of the provider?

I think that it would be proper for you to list the name of the original provider. Maybe this has happened before to others, and no one has previously said anything. From your posting her behaviour appears to be less of a last minute emergency on her part and more of a pre-ordained plan.