You can creat a supplementary challan through your ESIC portal.You Have to take only 3 steps for that. 1 Open your esic portal and select the month for which you have summited wrong contribution. 2 After first step Select the option of supplementary challan given below the monthly contribution and put the value manually like Esi no.,No. of days. 3 after putting the data of all employees please submit the contribution and creat new challan.you have to deposit the difference amt.between your previous challan and new challan created by you. But you can only increase the days of contribution.