I'd put her ass and your inconsiderate roommates ass out on the street. How the shazbot! did random dudes get your cell phone number? Someone had to have given it to them...reminds me of a couple friends of mine that had some chick leech on to them kinda like this. Friend 1 (your position) ended up getting mumped because he confronted those two after about a month, then a week later, the two moved out without telling him, leaving friend 1 to have to pay full rent alone until he found another roommate. Only bad things can come of this...