Indigo Airlines — Why charging extra for online payments?

Address: Gurgaon, Haryana, 122 002

Website: www.goindigo.in

Dear sir,
I had booked indigo ticket [pnr: udcrht] from the indigo website on dec 29, 2016. I was charged a convenience fee of inr 600 for payment of the fares through credit card.
When, at this point of time government of india is pushing for online payments, an indian company for its indian operation of flights is levying considerable amount of money for online payments. Does not it violate the spirit of order passed by the central government?
Earnestly request a reply which will mitigate the issues faced by you to accept on line payments for which you are charging additional amount. Further, suggest a method for payment without penalising the customers.
Thanking you,
Yours sincerely,
Indranil bandyo