HDFC Bank — wrong billing on hdfc debit card emi

Address:

Ground floor lakshmi plaza, 560029

I purchased one TV and refrigerator from amazon using debit card emi option from hdfc .The actual billing shown in while purchasing was 1499.83 and 1782.00 for 6 months but i got a message from hdfc today with due amount of 3014.94 and 3547.96 which i have no idea how they calculated.i tried calling their debit card emi customer care number which is not connecting at all.