Reconciliation

for the FY 17-18 , i had filed my client's 3b and gstr1...in sep 2019 i was reconciling both gstr1 and 3b of 17-18 and i found that i had done some calculation mistake due to which tax in 3b was less deposited... so i made my client deposit the difference amount along with the interest in the month of sep 2019, in the hope that the errors and ommisions can be corrected upto the sep month of following financial year, as per act... but recently when i saw thr gstr9 format, there is no such option given to accomodate the above adjustment done by me...please help me regarding the same