Query related to refund on Export

Husain (Student) (55 Points)

13 December 2018  
I have wrongly shown export without payment of tax as export with payment of tax in gstr 1 of Dec 17.
Now while filling refund application it shows error invoice doesn't match.
Whether it is possible to rectify error in gstr 1 now .
And if not how to claim refund of that particular month.
Please if anyone have solution let me know