Refund of Export

Sir
My client has made direct export in month of July 2019 and Refund for same is received.
In March 2020 we have made credit note of Export due to Goods detined at Customs office outside India and where never received back to India.
I March 2020 return we have shown credit note in GSTR 1.
But while filing GST RFD 01A while uploading statement 3. we unable to file credit note details as the excel utility did not allow to file credit note. so we take gross export value while filing refund application
Now the Dept is given notice regarding excess claim of Refund.
My question
1) Once the goods is exported outside India territory water ? is it is treated export
2) Whether we need to pay difference of excess Refund along with interest ?
kindly advice me in this connection.
Thank You