Icici bank loan a/c

It is regarding loan from icici bank which I have taken in year 2008..amt 81000 it is pre approved loan which bank offered me on basis of my saving a/c in their bank..i did not applied for it and also not given any documents or any cancel cheques n all...i failed to pay back..i didnt even paid single instalment...to the bank...after 2 yrs some bank representatives..i dont know wether they are bank employees or from any recovery agency or working for any DSA of icici bank...they offered me settlement of the above said loan amt in 32000..in two instalments..of 16000 each..i paid them in cash i have receipts copy and settlement letter from the bank..after 1 n half year some other bank employees call me n asked about this loan a/c i said i have done settlement with bank of this loan a/c they asked me to show documents...i gave them copy of settlement letter..then they asked for original payment reciepts..i gave them..keeping photocopy of those reciepts..later they never called me...till date..i m using same mobile number till date..sum days back i again receive a call from bank regarding this Loan a/c i showed them same documents which i have with me..they are saying these documents are fake..they does not have any update in their bank system..now they are threatning me to pay 48000 against this loan a/c as a settlement..they are calling me n on my wife mobile again n again..they r not coming to my place..but calling at my wife''s place of work..creating problem for her..she is a teacher in a private school working on contract basis..they call on school landline phone and continuesly call for 20-30 times...now the problem is they get to know dat if they call on this school landline she will get into trouble..infact they got to know our weak point..so they are harrassing us..by saying we ll keep on calling this no till the time u dont pay us back the money..they dont call on my cell..they only call on dat school landline..and its getting really embarrassing for her in the school ...kindly help us to get out of this mess..I am not so financially well to pay them back such a big amt .please suggest what we can do to get rid of them...