Consumer Redressal

I have booked flight through easemytrip.com today (31.01.2014). it was return flight from Mumbai to Delhi. I have got the confirmation ID and all the details regarding my flight and the amount I have paid through online transaction from easy trip planner pvt ltd. sometime back I got the phone call from the ease trip planner and I was told that while processing the amount, flight charges were changed and I have to pay the extra amount which was 600/-. I booked the flight because I was getting the fare according to my choice and after deduction of amount from my bank account and getting the confirmation id from the website, I am of the opinion that the extra charges of which I have no idea should not be bear from me. Kindly guide me what is to be done in this matter.