Non receipt of refund cheque

I have filed my Income Tax return (manually) for AY 2006-07 in time, which involved a refund of Rs13000/--Subsequently as I have not received the refund, I approached the Commissioner of Income of the Circle (thru' post) and I was informed that  a cheque dated: 13-07-2007 was issued. I am sure that I have not received the cheque in question. However I have verified the statements of all my bank accounts(though the refund cheque referred a single particular bank account). Subsequently, I met Dy Commissioner of Income Tax,Salary Circle and explained the things and I showed all my bank account statements to show that the refund cheque was not credited to my bank account. He heard patiently and he assured that reissue of cheque will be taken but I am not getting any reply even after 18 months. What I have to do? How to proceed in this matter? Please suggest me / guide me