Refund on excess gst paid in imports

Now ,the govt charges gst on the assesible value at the time of import which is usually 20-30% more than the declared value by the importer. so can we avail refund for the excess gst paid at the end of the year?

i.e. in invoice , an item is for value Rs.100 but govt charges gst on a loaded value of rs.200. and collects rs 36 gst instead of rs18 .

so , can we get refund for that 18 rs at the end of the year?