Bills foreign country but ship to India only

I am issuing invoice to foreign country with IGST payment but service proving only in India and in gsr1 and gstr3b,I have mentioned zero rated supply.now GST officer is asking payment under CGST and SGST head since they are telling that this is not export and place of supply only in India. so should I pay GST under CGST and SGST since I have already paid IGST