Air India — incomplete refund.

Address:

600092

In reference to my flight from vienna to bangalore via delhi. Reference number - j43mn on april 17 (Ai154 vie-del) april 18 (Ai502 del-blr). Passenger names: andrea joseph e-ticket[protected], samyukta rajkumar e-ticket[protected].
Last 4 digits of debit card used: 0372. Mobile number - [protected].
Cancellation done well in advance 20 days before starting the journey as my visa was denied on flimsy reasons by the authorities,. Hence the cancellation was beyond my control. The total amount rs 45509.91 indian rupees. (580 euros). I got only rs 13, 851/-
Being a student this is not acceptable to me and i didnt get the refund full details. Please forward the resons so that i can seek legal remedies as other airlines refunded the amount almost in toto to my co traveller.