Parking Problem In My Society

My society's builder didn't allot any parking nor have my society's managing committee. Now for the past 12 years, my father has been parking his car at given parking under our block. Now all of a sudden a goon type man has started to park his car where we used to park our car for so many years and have been troubling us lately. He acts like a legit Gunda and we don't want to have any trouble. But neither we want our space to be taken away. We contacted the chairman of the society but he denied to help to say the parking has not been allotted to anyone and he can't help us. My father is a BP patient and he gets riled up and is under too much stress for the past few days. Please please help me know what can be done as we've under too much mental stress for the past few days.