1. You shall have to submit some evidence in support of your claim as given below:
a) that your mother had taken the loan and agreed to pay interest@28% per annum.
b) the blank cheque number.
c) that she had rep[aid Rs.2 lakhs to the mediator.
2. Your steps of taking and repaying loan is totally incorrect and it is difficult to prove your points without submitting any evidence.
3. However, lodge a police complaint against the mediator and the lender for harassing your mother even after she had repaid the loan taken from the lender.
4. It is to be noted that RBI permission is required for lending money commercially against payment of interest and no body can charge interest more than what has been prescribed by RBI.
5. Even if the lender has license for money lending against interest, he can not charge interest @ 24% per annum which is too high in comparison to what has been prescribed by the RBI.
6. Police can conduct a search and trace out the blank stamp paper signed by your mother and in that case you can easily prove that there has been no agreement as yet since collecting blank but signed stamp paper for writing matters later on thereupon as per convenience is illegal.