Actually surprised by the positive responses for the sp here. When I read this, I was thinking about booking I had last week which was an outcall. I usually store the cash in the same place, however I was rushing and put it somewhere safe, too safe and forgot where it was. This was the first time something like this happened to me on an outcall.
It was just before the girl was meant to arrive and I had no idea where I had put it. I went to an ATM to get more, one that I could get back to mine in time, however it was out of order. Obviously I panicked a bit as she was about to turn up and I'm not home. I fired off a text to the agency and explained the situation, however I wrote in the text any time I'm late and she has to wait outside you can knock off my booking, they were perfectly fine with that. Luckily I got back 10 minutes late but she hadn't arrived yet.
I expect if i'm late for an exact appointment then it should be the norm to expect it to be deducted from the time, and a bonus if she doesn't (regardless of reason, at the end of the day this is a business relationship not personal).
We pay for their time! If we're late it comes out of our pocket, and if they're late it comes out of their time.
Granted she could've behaved in a different manner, however with all due respect to the op.. I don't think it's right to expect her to accommodate the op's failing.