MakeMyTrip India — unable to book

Address:

560001

I am trying to apply coupon code that i have but i am unable to put it.
Even after multiple attempt to call makemytrip i as unable to reach to there customer call center.

I need this to book as soon as possible or else the prices will increase. I am using netbanking and multiple times it's failing.
Makemytrip should help me. I don't expect this from a company like makemytrip.