Air Costa — not refunded my amount

Address:

Bangalore, Karnataka, 560002

I have booked the tickets on feb 22 2017 on aircosta website and then in april i get the messgae that airline is closed we will refund your amount within 20 days
Airline was lb613 dt 28th june
Confirmation number 02t1tu
Total 4 tickets amount 13000.00
When ever we mail they say we will refund in 20 days no telephone is working these people are really fraud