Harassment by college authorities

Respected sir I am a PG student of aerodynamics in BIT Mesra. I am a day scholar as I also have to look after my ailing mother .I use bike to reach college. 14th of august 2015 a female classmate took my bike for a ride within campus. We were followed by security and my bike was seized as 2 wheeler is not allowed for students, which we were not aware of.While the staff may use vehicles. My parents are called on 17th of august 2015.The dean of students and welfare threatened me of termination. He forcibly wants to allot me hostel for the misconduct. He has even threatened to sell my bike and build hostels.Allegations are that I have allowed a female to ride my bike. I have already given him apology letter signed by our dept. head but all efforts in vain. He has seized my bike without my consent till my parents meet. I am coming to college from 3 weeks and none of the guards stopped my bike to enter the campus but yesterday they seized all of a sudden. please tell what initiatives shall I take if college dean returns my bike but forces me to join hostel.