Hi,
As you said, I would like to clarify first that no employer can allow any employee to work on a National Holiday without prior permission from the Shops & Establishment inspector or Factory inspector, with a satisfactory reason.
In case they have obtained approval for the same, they must provide Compensatory Off for that day and also pay the salary or wage for that day at a double rate.
Most employers are not aware that without inspector permission, they cannot act against the law. Due to a lack of knowledge, they often follow their own rules and regulations.
In my career, I have encountered many cases like this where organizations do not adhere to the regulations, and directors or owners pressure employees to work on holidays.
In your situation, you are entitled to receive compensatory off for that day and also the wage or salary for that day at a double rate.
I hope you are satisfied with this information. If you have any doubts, feel free to reply to me or refer to the Shops & Establishment Act for more knowledge.