Courier service outside India under GST ACT

DEAR ALL

PLS ADVICE WE ARE A COURIER CHANNEL PARTNER OF DTDC COMPANY.WE COURIER THROUTH DTDC TO OUT SIDE INDIA.DTDC AND WE LOCATED IN CHANDIGARH UNDER GST ACT BUT DTDC CHARGES IGST ON EVERY SERVICES (GST ACT UNDER SEC 12 (8)) PLEASE ADVICE WHAT TYPES OF GST CHARGES AS A COURIER CHANNEL PARTNER. IGST OR CGST/SGST WILL BE CHARGE BY CUSTOMER 

 PLEASE ADVISE 

REGARDS SUNIL