HDFC Bank — extra interest charged on no cost emi on credit card.

Address: Grey Orange India, Orient Bestech Business Tower, Block A, Sector 34, NH-8, 122004

I bought One Plus 7T on[protected], using my HDFC Bank Credit Card with the option of No Cost EMI.
The actual price of the product was INR 39999.0 and i made payment using credit card with No Cost EMI option. During payment i checked the bill breakdown as : INR 38998.36 (price of product) + INR 1000.64 (discount offered by merhcant ---- Excluding 18% GST)
And it was mentioned there that INR 1000.64 will be charged as Interest rate for No Cost EMI later.

So, i made a payment of INR 38998.36, later a loan was sanctioned on my card for a duration of 3 months.
The sum of principle amount for 3 months was equal to : INR 38998.36
But the sum of interest rate for 3 months was equal to : INR 1115.5 (Excluding 18 % GST)

Thus the total sum now equals to : - INR 40113.86 (Excluding GST).

Now the difference in both sum:: total amount in loan table of Credit Card -Amount for No Cost EMI on oneplus.in
= INR 40113.86 - INR 39999.0
= INR 114.86 (Excluding GST)

The query here is:- Why i am being charged more interest rate than the amount shown me on OnePlus website?
This is fraud.

Either you should have informed me earlier. This is not the official way.