How to edit submitted gstr 1 for april 2019

Hi,

I made a mistake in GST number for one of my retailer in one invoice in April. Now I have submitted the GSTR 1 to GST Portal. That invoice is not uploaded due to error in GST number and I am unable to make changes in GSTR 1 to add that invoice as I hv already submitted it.

So what I have to do now to add that invoice? Coz the retailer will not get ITC if I don't upload the invoice. Plz help.