HDFC Bank — High interest and high overdue amount payment

I bought an AC using HDFC debit card EMI loan. I paid all my installments on time along with an interest of 16%. Still for the last installment they charged Rs.531 for delay of 2 days where 95% of the amount was paid, 5% was not paid so for that 5% o[censored]npaid amount I was charged Rs.531. These guys are blood sucking, they can debit any amount they feel like to get. Please take action for this soon.