HDFC Bank — no cost emi at hdfc credit card

I have bought Nikon DSL camera D 5600 for rs 46000 at no cost EMI from AMAZON . I opted for no cost EMI option which HDFC Bank was also offering on debit and Credit cards . It said that the interest shall be charged at 13% but will be discounted by the bank . But it has not been done so far . I have paid two installments.