False allegation by HR department on my Distance Learning Institute

During background verification process, my employer (HR Department) initially questioned on my Distance Learning M.B.A. degree. I have explained them the process of verification, post which after 2 months they are questioning about the Institute's location. I have enrolled for M.B.A. from Mumbai branch and that franchise doesn't exist any more. However, institute do operate from other locations and primarily through online mode. My organization's HR team is now questioning about the same and threatening to take a strict action against myself. Please help.