Ibibo Group / Goibibo — Cashback not received

Address:	Darjeeling, West Bengal, 734005
Website:	goibibo.com

I had booked a ticket on 29th August, 2016 and was eligible fof a cashback of Rs.1200 within 45 days which has not been received yet.
I contacted Goibibo several times, initially they replied that they are processing it and I will receive it by next week. When these next week changed to a month, they replied that you are not eligible for cashback as the value required was 5999+ and your account was debited with 5847. I informed them that the value was 6347/- which was paid as 5847/- via Bank and 500/- via Gocash. But they are saying that it was mentioned in the terms and conditions that the value should be only the amount deducted from bank and not paid via Gocash. I am damn sure that it was not mentioned there and this terms and conditions are updated only after August. They are neither providing me the copy of the Terms and Conditions of August infact asking me for the screenshot of the terms and conditions mentioning that the Gocash can also be used. Is it not the Company's duty to file its papers upto disposal of all the cashbacks?
This is why they ask for 45 days time to release the cashbacks so that they can change the t&c by that time