(2) Any person aggrieved by such order may, 2[ on payment of such fee as may be prescribed and after depositing the sum imposed by way of penalty under section 50 and within forty- five days from the date on which the order is served on the person committing the contravention, prefer an appeal to the Appellate Board: Provided that the Appellate Board may entertain any appeal after the expiry of the said period of forty- five days, but not after ninety days, from the date aforesaid if it is satisfied that the appellant was prevented by sufficient cause from filing the appeal in time: Provided further that where the Appellate Board is of opinion that the deposit to be made will cause undue hardship to the appellant, it may, in its own discretion, dispense with such a deposit either unconditionally or subject to such conditions as it may deem fit.