Promisory note

Hello, sir/madam,I would like to discuss few things about my parents..they run a chit fund business at home which is unregistered the problem is my parents have given huge money for a person for interest and through chits he absconded.It happened two years before From then my parents are paying interest to the persons from whom we brought as we issued promissory note for them Now we sold all our properties and paid them the Principal amount. we are asking them to give back our promisory notes but they are blackmailing us for the interest amount. and i used to give them details about chits in written in a peice of paper every month. even that we have cleared now.they are influenced highly and started blackmailing us about filing civil and criminal suits against us..iam married now..does it really becomes a problem if they file suit against us for chits.Now my parents own only one land for their survival they are trying to occupy it what we have to do now Thank You, With Regards, swathi.