You are right is to reduce the amount and monthly rest balance after payment of your EMI your principal amount should be reduced so that your interest should be charged properly in case your bank is not providing you deduction in your principal then you have to write the bank and incase Bank do not short out your issues you have to write to the banking ombudsman and the ombudsman man will start of the matter within 30 days if you do not receive reply from banking ombudsman within the stipulated time you can file your complaint with the consumer forum against the bank and ombudsman