Working hours for officer employee

I am an officer in a public sector bank. often my higher authorities insist that i should sit in office after 5'o clock citing the reason that i am an officer and and officer is duty bound but not time bound. Hence every day in addition to normal working hours i.e. from 10 to 5 i need to work 3 hours more. The work load entrusted upon me cannot be finished even if i work like this also and any lapses i would be accountable too. Therefore my questions are: 1. Whether the 8 hours working norms are applicable for officer category employees? 2. Whether the officers are work bound and if yes what is quantum of work they need to do every day 3. whether i get protection on my lapses due to the overload o 4. Does this a kind of a forced labour and exploitation as there is no regulated working hours and overtime payment. 5. Whether an officer employee can be insisted to work/ appear in the work place on weekly holiday for office related work or any other work like conducting banks recruitment examinations or handing over the questionnaires kept in banks safe custody.