Discrepency in amt

Location/place: Jaipur

Name of company/service: ICICI bank / car loan

I have taken a car loan in the month of by the name of my mother Krishna Devi Agarwal. I have paid all installment as on today, when I have asked from the bank for NOC, they are saying that Rs. 520/- is due for overdue payment whereas every payment has cleared from pur bank through ECS so there is no question of overdue payment but bank is trying to delay in issue of NOC for my car.