The bank had seized the vehicle on the ground of non-payment of the loan amount, this was in satisfaction of the loan amount and no further claim can be made by the bank.
More so the loan amount was taken in the year 2005, and its EMI were being paid from that time itself. The non-payment of any loan amount and its recovery has to be done within 3 years from the period it becomes due (July, 2006 onwards). The time limitation for filling suit for recovery of any cash debts is 3 years according to the Limitation Act. In the present case in the year 2017 after more than 11 years no bank will seek the repayment of loan amount.
What actually happens in such cases there are few Goons who operate as recovery agents for the Banks and other Financial institutions, these Goons search out for dead loans which are assigned the status of bad debts by these institutions in their account books, they collect the details of the debtors and start harassing/threatening them by making calls and visiting them at their place of residence or work which ever they got. These Goons even harass the other relatives and guarantors of the debtors.
If you check with the concerned Bank they will tell that there is no demand made by them for recovery of debt taken by your father and the debt got recovered after the vehicle was taken by them from your father's possession. After clarifying all doubts with the bank, if you still get the calls from the so called Bank agent, lodge a criminal complaint against that person for criminal intimidation.