Goibibo India Private Limited - Charged more than the payable amount

I booked * tickets from goibibo app availing the no cost EMI offer. As per the said offer, there are no processing fees or down payment for these transactions and the bank will charge GST on the interest component of the EMI. However for the card I used, under * month EMI option, there was no interest charged by the bank. The total amount payable was Rs. ***** (for * month EMI it showed Rs. ****x*). I completed my transaction and was surprised to see that I was charged Rs. *****.** (Rs. ***.** excess). I have been trying to contact them via app/phone/twitter. But they are very cunning in escaping out of having to directly speak to the customer. There customer care numbers are all limited to IVR. You cannot directly speak to any person. I hope for attention to the matter from the company representatives.