Regarding excess working hours & completion of articleship

Plz help... I've served 3yrs of articleship wid my principle. I used to wrk for almost 60-70hrs in a week. and taken leave for 4 extra months. Now at the time of cmpltion of articleship, my principle refused to sign 108 n saying that u hv to do extension of 4 mnths. But as he is demonic, i dnt wanna work wid him. Plz tell me, whether is it possible to do the article ship extension wid other ca? What is procedure? And it is compulsory to get 108 signed from Principle? plz help. Because of mentally harassed by him & every days disputes, doctors detected dat im a diabetic patient. My life ruined because of him..please help...