Excess sales showed in GST

Aslam Basha (Accountant) (30 Points)

06 February 2020  
i have query on GST. plse help.
in May 2019 we have showed excess sales of 65 lakh. And filed both GST 3B and Gst1 for the period, which is not sales actually.now we came to know this error. plse advise in detail how to rectify. Thanks in advance

Aslam