How to make changes to already amended invoice for a tax period ?

If I already amended an invoice of FY 2017-18  in Aug GST period then the portal does not allow to amend the invoice in Sept GST period. showing error message "already amended in last tax period so not allowed now". what is the solution?

in Aug GST period, I amended the invoice, changed the TAXABLE VALUE AND TAX but keep the INVOICE DATE and INVOICE NUMBER same. but as per client, I need to change the invoice date. Not possible now I guess. then what are the other ways ?