error in GSTR 3B

hi
we r exporters and in the month of August we did exports both under payment of IGST and on LUT
while filing GSTR3b we entered they value of Export made under Igst under 3.1.(a) i.e local supplier instead of (b) i.e zero rated export supplies.

now the tax liability is deducted but has not linked with Icegate server and will not be moved for refund.
as of now there is no scope for making changes in gstr3b since the returns are already filed
please guide us with any other available options

thanks