Export of refund with payment of tax

one of my client is exporting cattle feed goods to bhutan with payment of IGST. Inorder to claim export refund in GSTR-1, shipping bill no. and port code need to be update.

In our case custom clearance details are as follows : 150-969-85/GP11 & DRC-79-20186061.

Can anyone help me in this case what will be shipping bill no. and port code? If this is not the actual details than how do we obtain the same?