I'll start off by saying this outright so people know my stance, this may seem like I'm defending n5m/42g but I'm really not. I think n5m/42g is so far inferior to Ginza, I see no reason for me to visit these establishments anymore.
I was never a n5m regular but once upon a time I was a weekly regular at 42g for a very long time. 42g has a setup where the girls can see the punters in those waiting cubicles from the girls waiting room, this is so girls can see the punter before the punter can see them. The obvious reason for this setup is so girls can avoid any friends/people they know in their day-to-day lives, or just punters they don't want to see for whatever reason.
Now I'd assume n5m would also have the same system (i'm assuming as i've never got close enough to any girls that works in n5m to confirm). Tbh, i think any reputable shop should have the same system, Ginza Empire has the same system too, it's completely up to the girl to come out to join the line-up or not.
So to play devil's advocate, since you said you saw the girl you booked in the corridor, i see 3 reasons why the situation you described could have happened.
- The girl actually felt sick and wanted to go home right after the punter before you and cancelled (you were just unlucky)
- Reception accidentally double booked and made a random excuse, it happens, even Ginza does this sometimes (although very rarely)
- As you described, the girl saw you and didn't want to see you for whatever reason/she shadow banned you from seeing her and told the reception. The reception, didn't want to hurt your feelings said she cancelled because she is sick
Again, i'm just playing devils advocate here, i don't actually know what happened but i find it unlikely it was some sort of unethical booking practice ( I do believe some shops do this, but prob not n5m).
"Never attribute to malice that which can be adequately explained by stupidity"