Mental harassment at workplace what action can i take

Dear Sir, I am working in IIT as assistant professor on a regular permanent post. I recently applied for LTC from the approval of chair/HoD, and the registrar issued me the office memorandum for the same, stating that my LTC as well as my leaves are approved. But on intervention of Director, I have been asked to justify the leaves (which are already approved). My start of journey for LTC is to start in couple of days and the administration is asking me to furnish the plan, tickets etc for the same. As they have already approved my leaves, they are just harassing me. What shall I do?