I`ve had lots of trouble with parlours as Im a student and can only do a few days a week, (usually weekends as well) they seem to drop girls if you arent available as and when they wish. But how I normally look for a good place to work is look at the PNet reviews to see who is busy at the moment.
There are lots to choose from, so better to go with a well known name than an agency with no or little info on them. The reviews can tell you a lot about the set up and the attitude of the girls (crucial cos if they suck at there job they may lose you regs as well )
I would stay independant as the next few weeks to Xmas are always busy, have you tried all avenues of advertising? All self employed buisiness takes a while to get regulars. It will get better
Bear in mind that there have been an awful lot of raids in the south recently, operation sentinel? on the parlours, so maybe have a back up if one gets hit. Good luck x