HappyEasyGo — HappyEasyGo not refunding ticket amount.

HappyEasyGo is not refunding my ticket amount of flight which was from Nagpur to Amritsar ( Layover at Delhi). This flight was cancelled by the airline due to some unavoidable circumstances and after completing the airline procedure of processing amount it says the amount have been refunded to HappyEasyGo but HappyEasyGo is not refunding my money as while uploading file it says 'Undefined' error. And tried from their site, app all possible ways and by compressing file too.

Also I have mailed HappyEasyGo but no reply since last 10days.
Tried calling at customer care number but no one is available to take call as they don't have any executive to attend customers.

My amount of ticket is 4827/- and HappyEasyGo is not refunding my money even though they have received the amount from Indigo Airlines.

Please help me with this issue and process my refund amount as soon as possible.