(3)(a)No decision or order under this section shall be made so as to prejudicially affect any person unless such person is given a reasonable opportunity of making representation and if, he so desires, of being heard in his defence.(b)Where the Board or, as the case may be, the 358[Principal Commissioner of Central Excise or Commissioner of Central Excise] is of the opinion that any duty of excise has not been levied or has been short-levied or short-paid or erroneously refunded, no order requiring the affected person to pay any duty not levied or paid, short-levied or short-paid or erroneously refunded shall be passed under this section unless such person is given notice within the time-limit specified in Section 11-A to show cause against the proposed order.