Indigo Airlines — Non reclining seats

Address:	Pune, Maharashtra, 411009
Website:	book.goindigo.in

I was flying Kolkata - Pune via Ahmedabad on 18/02/2016. My flight number is 6E 0202.
WHen I was checking in I was told that only non reclining seats are available.
I was shocked to know that even though I am paying the same price why am I being given non reclining seats.
Later when I boarded the flight i was even more shocked to see that my seat was non reclining since the seats behind me were being sold at a premium of Rs. 600 for extra leg room!! So basically Indigo was charging me full price and providing me a non reclining sea and saving space. Moreover it was charging premium for the same saved space to as an XL seat!!
I would like to know whether an airline be allowed to do such restrictive practices?