Air Asia — refund of airport charges as per revised govt. rules

I had booked fights as per following details:

Booking no. — rwugmk booking date — 26 may 2017
Flight details — new delhi — bagdogra
No. Of guests — 4
Air asia big member id — [protected]
I understand that as per the recently amended director general of civil aviation ("dgca") guidelines, udf (User development fee) & aat (Airport arrival tax) for travel from/to igi airport (Delhi) has been revised and no longer applicable.
Your airline has not refunded the amount charged in the tickets.
Pl. Refund the amount by crediting to my account and confirm.

With best regards,