They can't say that the session 'isn't finished.' They just failed to provide certain services and/or time. A 'session' (meaning, loosely, pay for play) did take place.
P411 can't refuse the OK because the session 'isn't finished.' Either you met and had a session (whether or not all planned activities took place) or you didn't. These girls are refusing to give an OK, because they want you to give them more money.
As for the porn star verifying you through your personal identity... it's a time-honored way to screen. However, be careful when sharing that info (for instance: it would be a REALLY BAD idea to screen that way with the two crazy girls you met). Once you accumulate enough references, you'll always be able to find someone who'll accept a date with you (although some women might require additional info in addition to references, as is their prerogative).
As Tobi said, I'd just cut your losses, and move on. Learn a lesson from dealing with these two thuggettes. I'd just tell them you'll contact them to schedule at some point... then just don't. Don't try to argue with them, don't try to get your OK. Just be happy you escaped without any greater harm than a lost night of sleep and a few benjamins.
See some nicer girls (like the porn star), get some more references, and you'll be good to go