Extra interest charged by a finance company.

I had a loan from DHFL. They are charging interest fraudulently before the disbursement cheque getting banked. say for example, when you submit your file say on 1st jan 14 and finally disburse the loan on 25th Jan 14, (date when the money actually gets credited to builder account) they will charge for the interest from 1st on wards citing that they had processed the case on 1st itself when we applied.

Also when I closed the loan, they have charged me interest for the entire month of January when I had handed over the draft from other bank on 11th Jan 14 citing company policy. Are they justified in open looting of their clients and does this not constitute fraud and cheating on their part with the clients? What is the legal remedy available to me?