There are two ways of getting an erotic massage in Santiago. Massage parlors are one way, while some of them are brothels. You can find those places in apartments around Santiago. You’d best ask around, or look for ads in newspapers. There are few that advertise online like the Amazon Spa (http://www.amazonaspa.cl/) at Av. Manquehue Sur. La Mansion Del Masaje (http://www.lamansiondelmasaje.cl/) is one of the super-secret ones that don’t give you an address right away. $100 will get you a 4-hands massage, which is a bargain.
Saunas are your second option when you are looking around for a good rub and tug. Try for instance Sauna Mi Tiempo (http://saunamitiempo.cl/) at Bombero Núñez 230. There are many more, but bear in mind that many are run by and targeting the gay community. So better ask in advance if that’s not your thing.