(23M) molesting by old man?

I (23m) was traveling by train to guindy, naa paatuku oramaa ninutu irundhen. Train was a bit crowded but there was enough space for the old man to stand. Konja neram keluchu en private part la kai vechu lite ah thechan. At first I thought it was accidental but neram poga poga romba repeat panna start panitan naanu en kai vechu avan kaiya opposite la push pandren avanum force pandran. Aprom train vitu erangitu catched another train. Enaku idha type pandradhuke awkward ah iruku. This is not my first time, naa school ku train la dha poven since 7th, faced this situation many times during my school days. All were old men. How do you guys deal with this situation? p.s. not sure flair is right and this happened in chennai so posting here