Interest leived on Educational Loan.

Hi All, I am Kamesh, I got loan from Government BANK for about 10 Lakhs 2010 for abroad education they have given me Moratorium period of 4 years my repayment started on 2014. The Interest calculation during these periods were Monthly rest, that they calculate the Interest every month and add it to principal by end of every month, so for next month they calculate the interest for current principal+interest for previous month. Though they use Simple Interest the principal keeps changing. When I took to Bank Managers notice he first told that we would not compute Interest for Interest, after checking all my documents he says that you would be charged Compound interest. Now my loan has amounted to 19 Lakhs, Manager told me that he would calculate accordingly and revert remaining back, so I paid the entire 10 Lakhs. Now they never respond to any of my emails or calls they give lame excuses to while away my request. Is it legal to charge Interest to Interest on Education loan for Foreign Education.