HDFC Bank — Credit Card EMI Interest charged falsely

Address:	Mumbai City, Maharashtra, 400042
Website:	www.hdfcbank.com

I booked a phone Motorola G3 phone from FLIPKART on 13th Sep 2015 worth Rs. 12999/- on EMI with HDFC bank Credit Card for 12 months. Since it was taking time to deliver I cancelled my order on 15 Sep 2015 by calling FLIPKART customer care and asked them to reverse my amount in source payment that is my HDFC credit card account. On the same day I got a message from HDFC BANK that my transaction of Rs.12999/- is reversed. When my statement for Sep-2015 got generated on 18th Sep 2015, they reversed my Rs. 12999/- with 18th Sep 2015 as reversal date and also charged 1st month EMI(1020.22(principal)+140.82(interest)+19.78(Service Tax)) in the same statement. In my next month's statement, they added 12999 minus (1'st month principal in EMI) equal to 11978.78/- as debit transaction. My concern is that when my transaction is reversed before the statement date, how can they charge interest+service tax to me. When I am calling on phonebanking they are saying that Interest+Service Tax cannot be reversed. Please help me out here.