Excess output tax wrongly entered in gstr3b

Dear All,

 At the time of filling Aug17 GSTR 3B , I wrongly entered output tax liability of Rs:133664/- instead of rs:113664(actual) under SGST head ,but under CGST head i entered Correct Amount(113664) And that time paid excess of rs:20000/- under SGST head and filled. I already filled Sep-Nov gstr3b till now but i did't adjusted the excess tax amount. As per my knowledge it should be rectify only through GSTR3,which due date is suspended by govt. till mar17

Please help me whether my action is correct,if not What should i do

Please advise

Thanks in adv