If you read the FAQ, it lists a number of reasons why a provider's reviews might be pulled.

You might want to contact Bruce to confirm your appointment.  She's probably left the agency.  If I remember correctly, she left once before and came back.  She might turn up as an independent in a couple weeks or so.

If she retired, she may have had her profile taken down.  If not her, I'm sure Bruce would do it if he's able, especially if she did something that might show up in bad reviews.  It's not in his best interest to have Pretty Maids get bad reviews, even if he fired her over it.

There are plenty of incredible independents in Vegas to choose from if you have the time.  If not, Bruce should be able to hook you up with one of his other girls.  I think Cami is the most popular.