Tds notice for fy 2011-12

My client is XYZ Bank. they paid interest on which they deducted TDS @ 10% 194A. But notice came that TDS should be deducted @ 20%. That means they are saying a short deduction of Rs3530+interest[i.e. (20-10)%]. Bank system has also deducted 20% automatically. But bank filed a return according to 10%. Dont know how to deal with the situation please explain.

Thanks in advance