Citibank — Cheque Fraudulently encashed without verifying Signature

I have got my salary account with CitiBank and on 3rd Feb 2010 my cheque book was stolen for which i called citi customer care and followed there instruction to request stop payment request using cheque.On 24th Feb 2010 , Rs.20,000/- was withdrawn using same cheque book and when I enquired they simply said stop payment request was not registered due to system error.They have got call records where i repeatedly mentioned my cheque book was stolen.Then I said that those cheques were not signed how can you process them to which they replied it can never be processed without verifying signature.I demanded for copy of that cheque and they took long time to reveal that signature was not matched and we are sorry for that.Till Now I have neither recieved cheque nor the amount and I have gone through mental trauma as i urgently needed those money but Citi's approach is very casual.
Kindly let me know how to proceed on this.
Thanking You,

Anil Kumar Yadav.