I was told by lab that hiv RNA pcr test is accurate after 72 hours, was I lied to?

72 hr is too soon. This test takes a few days to become positive; 72 hr is too soon. Probably no intentional lying; more likely miscommunication or misunderstanding. In any case, DNA testing (RNA, DNA, PCR, etc) is never enough to diagnose new HIV infection; also need an antibody or antibody/antigen test. Best test(s) depends a lot on nature of exposure. See doctor/clinic experienced in HIV prevention & diagnosis.