As per RBI regulations they are not allowed to charge any convenience fee.
I had asked them to refund the fee for the ticket booked, to which horror of all horrors, I was told not to book tickets from them.
I have whole story in this thread.
https://twitter.com/blogaks/status/1113688842723160064
They have absolutely no regard for rule of law and their customer service is the rudest possible ever.
Better book directly thru airline website and save yourself some headache.