Overnite Express — delivery not done, no refund given from the courier service

Booked a courier from calicut to new zealand on aug 8th, 2018.
Courier was informed returned on august 28th and the branch manager promised a full refund of the return, untill now there is no response from the branch manager nor any of the staffs of the firm are not giving any proper response.
Who would the higher official of a branch manager?
Even the customer service is very poor, they are not ready to hear the customer complaints.
Why are such people appointed as customer care executives?