How to get back our money back from party

Respected eminent seniors,

                 I am working for one company who is having their account in one nationalized bank. One day suddenly transfer some of an amount from company’s said account to one another company’s account on fraudulent instrument. Our bank and opponent’s bank has not taking efforts to get back money, instead placing police complaint. During the period I contacted the said person from whose account the said fraud committed. It is revealed by him that the said fraud committed by his closed friend by using his stolen cheques. Now that person is ready to return back our amount and accordingly he had tender us a registered undertaking-cum-affidavit. I may kindly suggest under what instrument and how we can take our money back.

Ramesh S.