A lot of those girls double-book if you're playing the "instant gratification" game.  If you simply called and she said, sure, come in now, it's most likely she's been saying that to EVERYONE who calls and says they want to come in.  Lots of the guys say they're coming in and then never follow through, so those girls have to double-book if they have no way of (or aren't even bothering to try) verifying that you are a serious and reputable client.

Did she screen you?  Did you have to book in advance?

Don't be surprised if you try to see providers who don't screen or don't set their appointments in advance and then they don't answer your calls when you get to their hotel.  A lot of the time, some other guy just got there before you.

If she screened you and you had an advance appointment, now that's another story...

Either way, sorry this happened to you.