Place of supply of Custom clearance services query

Having a doubt in place of supply for a transaction of imports.

DHL is providing import customs clearance services to the importer. Dhl is paying all custom duties and other taxes for clearance. 

Now dhl is raising consolidated invoice to the importer for their custom clearance service charges alongwith recovery of the custom duties paid on behalf of importer. 

Dhl paid igst while clearing, so in their consolidated invoice they are charging igst only for their services also. The issue is, dhl and the importer are in the same state. Then why dhl is not charging Cgst and Sgst on their charges. Is the place of supply for the service provided by dhl also "Other territory"? Please suggest the relevant provision notified by the government in this regard. 

Thanks