There are multiple services that book many and/or few stars. Any agencies or booker will require some form of screening if you’re going to meet someone. A few/at times they may even require some amount of deposit/retainer.
Here is or less a current list: Dreamgirls (thegirlofyourdreams.com), Exclusive Model Introductions, Exotica Models, HelpUbookHer, Hetaera Agency, Lourdes Enterprise, Perfection Models (no website, p411 profile: preferred411.com/ProviderPage_Agency.cfm?cid=65503), The Luxury Companion, Top Level Companions.
Le Vip Collection may have a few.
there’re also bookers with no website such as
Vanessa at: pornstarassistant(at)yahoo(dot)com
Nina Reynolds at: ninasbooking(at)gmail(dot)com