My two roommates and I are moving out of a loft we were sharing with the prime tenant. We believe that the prime tenant has been charging us more rent than what is on her lease and has been pocketing the profit. When asked for contact information for the landlord, she tells us that the landlord doesn't wish to speak to anyone that she shares her apartment with.
My question is, as this is not a rent-controlled apartment, is she legally allowed to overcharge on rent? And if not, what kind of action can I take?
Also, if I am not supposed to speak to the landlord, am I allowed to contact her to inform her of our suspicion and obtain confirmation?