Discrepancy in it refund being adjusted against previous yrs

Hi

I was expecting a refund of IT for assessment year 2012-13.

Recently, I received a mail from CPC, Bangalore that the refund determined is being adjusted against outstanding demands from previous years (2008, 09 and 2010) under section 1431a! The Tax calculation in the previous years have been upto date and there has been no need for additional payments required for me as per the assessment acknowledgements. So, I dont understand how suddenly IT dept finds a discrepancy when the due is on their side.

I followed some of the forums here, which suggests visiting the AO might solve the problem.

I have no idea what an AO means and where the great chap sit? To add to my woes, I am out of India at the moment and need to settle the discrepancies within 30 days of receiving my email, which obviously is not feasible for me for a personal visit to AO.

Any help will be useful.

THanks in advance.

Subrat