Reliance Digital — Purchased laptop on 0% emi but now interest is being charged

I have purchased dell laptop from reliance digital v3s mall delhi..i have been told by mr. jai( sales person)that it is 0% 6 emi's and no charged would be levied on these emi's which is clearly mentioned in slip which is being generated after swapping my hdfc debit card in reliance digital. But now i have charged emi with interest and the sales person mr. jai and senior mr. samsher has no answer for that...they only say" what we can do, it is bank charges".
this is very horrible that reliance digital is selling product by telling lie to the customers..plz look in to matter and take appropriate action.