£1800 pw = 3 Guys per day... not a lot for a brothel I'd have thought.
You've made a lot of dodgy assumptions there.
For my own (hopefully less dodgy) assumptions, I'll stick with the assumption that every punter goes for an hour at £120 with no extras, even though that's obviously not the case (e.g. 3 of her 4 reviewers on here opted for half an hour, including the OP of this review for his 2nd punt).
You're assuming she works 5 days a week. She doesn't, as per the current schedule on the Indigo Nile website and her own AW profile, she's only worked 2 days this week. However, I'll presume she averages 3 days per week. Based on 3 days, according to your calculations that makes the average number of punters 5 per day but that still wrongly assumes that she pays nothing to the parlour where she works.
When she says she makes £1800 per week she surely can't be referring to money that she either never sees (because it's paid to the directly to the parlour by the punter) or that she has to hand over. Most parlours take about £40 from a total fee of £120, meaning she probably gets £80 per 1 hour punt (assuming no extras of which she'll keep the entirety of those). Therefore the real sum should be 1800/80, which means an average of 22.5 punters per week. So that's 7.5 per day, assuming a 3 day work week.
Assuming she's available for a total of 8 hours per day (which sounds about right based on the hours stated on her profile), that makes her very busy indeed. So busy in fact that I don't believe the figure. Either she's exaggerating about how much she makes or perhaps she usually works more than 3 days per week, maybe others can shed light on that? Or perhaps she is just including money that she makes for/gives to the parlour.
You then have to add the fact that even though extras will boost the average spend per punter, many punters will go for 30 min meets, which means to make £1800 per week she'll need to see even more than 22.5 punters, probably quite a few more. I'd guess it would be around 30 punters if not a few more.